I'm referring to them as "one" because the elves are one race. They have as a race suffered the result of the Exalted March by being divided, those less fortunate forced into slums for 700 years. The history you so want the elves to forget caused this divide of City and Dalish elves. Now the city elves are forced to play by the chantry rules or face punishment. They are not given the luxury to live and believe as they want.
I have never claimed the elves should forget history. I have asserted that the Dalish shouldn't practice it as they do. I'm a great fan of history, but there's a clear difference between 'being aware of the distant past' and 'letting the distant past define you.'
You're equating races and polities. You are right that the Exalted March and fall of the divides made the distinction- but the distinction must continue be made after then. The Dalish elves are a different polity from the city elves (who themselves are not a unified polity), and the experiences of one can not be transcribed on the other. The Dalish themselves do not identify with the experiences of the City Elves- to argue that they face the same discrimination and prospects as other elves is not only objectively wrong, it is not even an argument or belief the Dalish have.
Nor are the city elves at this time, and for an indeterminate time going backward, being forced to believe in Andrastianism Or Else. The Chantry does not govern them or set out the rules for them- the local human nobles and kingdoms do. The elves do not under theocratic pressure- that charge would be more applicable in the aftermath of the Dales war, and possibly during the Dales themselves when Andrastianism was apparently strictly forbidden.
As for the Dalish, true they are not as persecuted as the city elves, but they live a harsh life in a different way; forced to defend themselves at all times and unable to stay in one place for long.
Such is their choice, and in some cases such is their responsibility.
And the reason for that all is, surprise surprise, the past. Is it so hard to understand why they cling so desperately to the past when they live the consequences each and every day? There are of course those who would claim they brought it upon themselves, in which case they can be safely dismissed as trolls.
I understand a number of desperate and flawed rationalizations for bad decisions and policies. It doesn't change the nature of such choices being, well, bad. Understanding is not validation.
The Dalish of the modern era obviously had no fault in bring about the context they grew up in. The same applies to the non-Dalish, and the non-elven, and everyone else who was born at the same time. I would hope we can all agree that people are not guilty for things set in motion before they were born.
But the further you go back in the past, the more opportunity, and responsibility, the Dalish can claim for their current state of relations- not solely, but enough to claim responsible for themselves rather than merely the impotent victims of outside circumstances. No one else makes the Dalish hold their current cultural views of humans and lesser elves- no one else made the Dalish choose a tribal diaspora rather than subjugation, conversion, and assimilation like most elves- no one made the Dales put a good part of Orlais to the sword- no one made the Dales trash relations with their neighbors by withholding aid during a Blight even as a city burned- no one else made the Dales close off their borders to even peaceful missionary activity- no one made the ancient elves fight amongst themselves, raise the veil, and fatally weaken their own civilization. These were all choices that elves made, not dictates or requirements imposed by outsiders.
Outside actors exist, and are important. There is certainly no 'deserve' in any of the circumstances for any of the elves- no argument of karma, no moral justification, nada. But outside actors are not alone in determining the shape and context and history of elven experiences in Thedas- and the Last of the Free Elves, being as free as they are, have more hand in what they choose to do than most.
How will they move forward with so little they know? For the elves to have a reliable and stable future, they have to learn and put to use what was forgotten. They tell stories of their gods, but how much of them is true, and missing the complete picture? Without information like that, they will only build upon lies and misinformation. They will have to reexamine some of their beliefs and adapt it to their lifestyle. But for them to do that reliably, we have to know more than we have learned in this game, because there are still parts of the lore that doesn't make sense. So, the past is still important, no matter how distasteful it may be.
Build new things, rather than reinvent the mythic old. It really is that simple.
In-universe, pretty much every human nation and culture in Thedas has existed for comparable periods as the post-Tevinter slavery elves. All human cultures were built on the ruins and remnants of Tevinter- and yet each Human nation has become a unique and distinct culture in their own right. The Dales created a new state and traditions and culture in three hundred years after Tevinter slavery- the Dalish have had seven hundred years, and not having a state doesn't mean that they can't create new practices or traditions.
Heck, Build anything, rather than have a social strategy of 'wait for the humans (and presumably Qunari and Darkspawn) to kill eachother off so that we will be left the sole survivors.' Create a new culture, going forward, rather than be dependent on an old and raggedly one with so many missing blanks. They don't need to base themselves off an identity of The Last Free Elves Who Will Regain The Utopian Past. There's nothing requiring them to do that or perish. Their culture is a result of choices, many of which are their own.
Also we don't know what Merril's mirror may do yet. If you were her friend, she doesn't destroy it after the events with her clan. As we have learned, eluvians are valuable for some key reason we don't understand fully. Restoring it cost a terrible price, but it may yet play a role.
This is a great appeal to the Farmer's Son parable (Fortune or Misfortune), but rather irrelevant to the results to date. Merrill's expected goals were vague, but unreservadly positive- Merrill's results were certainly not. Pushing the goal line a few decades for a turn around doesn't really change the occurance in the game itself, which was the frame of reference being raised.