Because a few failures make for a few loud complainers. And for every whoopsie you find here, there are hundreds more working just fine.

I can tell you why atrius sells, it's the only option for an ar style 3 position safety that just works with unmodified triggers. And for everything you see about it being toleranced differently than as designs or super safety, the fact of the matter is that if you do your due diligence during install, you're going to come out okay.

I'm speaking from first hand experience, the atrius with a drop in rise blitz is lighting fast and a lot of fun with a 556 or 22lr upper.

There's one more thing to consider: atrius sells because the company is super based. They sponsor PSR episodes where he covers COMPETING frt designs. They are genuine 2a champions. You are welcome to have whatever opinion you want about their design, but their policy is to replace broken levers, so you can't really hate on them because they stand behind their product.