I think it's mostly because Dark Urge can prematurely end stories which people may be interested in exploring, due to the urges. And they weren't wrong
I initially was excited to play Dark Urge and resist the urges, but once I came across that one specific camp scene which cannot be avoided in a legitimate way I deleted my entire playthrough. Didn't like that all choices in that scene are fake and forcing me into it. So I started a pure custom character after that, but eventually deleted that one too and went back to Dark Urge again because I wasn't going to allow that one scene to ruin my enjoyment of the character. This time I metagamed to get a different outcome from that camp scene and been loving it ever since.
For me that's most likely the reason why they warned people not to play it. I personally really do love Dark Urge and its lore, it feels fantastic having a customizable Origin player character. But that camp scene is just terribly designed. Locking 2 of its desirable outcomes behind metagaming is a terrible design decision, so it's not surprising to see a lot of people delete their playthroughs once they come across it when they don't have a legitimate choice in it.
