I don't think you know what game mechanics means. They don't even have access to lyrium much less the ability to refine it, and put it into philters.
Meaning that what is shown in gameplay isn't necessarily accurate to stated lore.
Though in the case lyrium and templars, the separation isn't that greatly reinforced or consistent.
Origins: Alistair, a trustworthy, good-hearted and honest companion who was a templar trainee recruited to the wardens before taking his vows tells you that templars may not need lyrium for their abilities. Something that's reinforced by how the Warden can learn the specialization and not have to take lyrium for it.
Dragon Age II: Templar Hawke is also not shown to use lyrium for his abilities. Some have said that he probably smuggled the lyrium in and that's how he got the abilities. But the lack of on-screen proof could lead to the possibility of Alistair being right and that the lyrium thing is just a system of control by the Chantry.
Yet, the comic and Inquisition add in contradicting evidence that suggests that templars do in fact need to take lyrium. However, the comic is a supplementary optional story for a series whose main entries are video games. Attempting to use the comic as a basis and proof for a retcon comes off as awkward and ineffective because not everyone will read the comic or even consider it "more canon" than the games. Especially if the background of the canon doesn't match with the canon of their playthroughs. (Bioware's canon has the Warden die while plenty of players kept theirs alive.)
Then you have Cullen's reference that templars don't take lyrium until after they take their vows and considering that he's been in the order for over ten years, Cullen's word should not be dismissed lightly. Which means that Alistair's theory has more credibility or how else do you explain how Alistair and the Warden can use templar abilities without the shown use of lyrium.
Another reason why the retcon makes no sense is because this blatant "backtracking" also adds an out-of-character moment for Alistair. The WOG retcon dictates that Alistair basically lied to the Warden, took lyrium behind his back and now the Warden is unknowingly tricked into becoming a drug addict.
Long story short Gameplay-Story Segregation is another way of saying that the writers' made an oversight in the classic rule of "Show and Tell".
But considering all of the contradicting stuff that the retcon created, you're free to ignore it. It's somewhat of a minor issue anyway, so feel free to fill in the blanks with headcanon and your theories or whatever will be just as valid as the canon retcon.
It would have been less of a headache if BW had kept the issue ambiguous.