I can't really find more than maybe 10-20 unique public cases of a System76 computer having serious problems. I don't want to toot our horns too much here, but that's just not very many people compared to our entire userbase. We're a company with the resources to develop open source firmware; it takes a lot more support from your customers than could be afforded by 10-20 (or 100, 1000, etc.) people to do that.
If you look hard enough, it's not hard to find examples of any computer manufacturer having issues with occasional units. That's just the nature of manufactured products (especially high-tech electronics). No company has a 0% failure rate, and any that claims to is lying. However, you can be reasonably certain that any company that's been around for a decade and a half (or longer) has a lot fewer failures than successes