Well that's the thing - elven legend claims this, but Solas seems anything but about mad laughter and being overly-pleased with himself. Yet another legend claims that Fen'Harel abhores wisdom and kindness, which - if we know enough about Solas - seems to be entirely antithetical to his actual character.
Question now is whether those legends were supposed to be put into the game as a sort of red herring, or a way to illustrate how little Dalish know of their gods or what happened, or is there a grain of truth in there? (though it may not be entirely not what we think)
All of it, really. Just drawing upon ways these same devices are used in other media. I know some people who were into guessing pegged Solas as ancient and some may have even been on the Fen'Harel trail, but in general the red herrings and the careful seeding of the character are meant to contrast with his actual character so when the reveal is made, things fall into place and we're already (likely) to know some things about him that would make us question those legends and might even be very sympathetic and even care about him.
As a secondary purpose, it emphasizes the Dalish guessing and infusing their legends with fears and even some degree of lessons, as happened with many systems of mythology we've seen in real life. Where we read between the lines and all as to how societies, especially in mostly pre-literate oral traditions, shaped their legends to reinforce mores and beliefs. And maybe a healthy dash of making things up as we go along in order to fill some gaps - which is then passed on.
It's all quite a fun thing for all of us nerds to go poking through.
I studied both literature and sociology (and my anthropology course was also very enlightening), so this follows.
I also think we're not done getting our presumptions or 'knowledge' about elven things turned around or twisted into a new light just yet.