I think the point of contention is with "Staff+" roles. I'm at a Big Tech company and we've seen lots of success with bootcampers, but I've noticed many of them hit a wall around Senior or Staff. Though I worked with an engineer who was super intelligent and a blast to work with and she is now a Staff engineer and was from a bootcamp. (At the time we were smaller and didn't really have any Staff level roles.) We've also had several bootcamp engineers move onto other Big Tech/FAANG companies so I have no idea what they're up to there.

I can see why folks might want to hide their bootcamp path if they already have past non-bootcamp experience they can point to. In all fairness, most engineers, whether top-10 CS school or bootcamper, tend to hit a wall around Senior or Staff. Without knowing the true denominator of bootcampers we've hired, I can't properly answer the question of whether bootcampers tend to do better, the same, or worse at these levels than average.

Everyone I worked with had a undergrad is CS/math/engineering and plenty had masters / PhDs. That's generally what the profile of devs at faang looks like. I'm sure there are some people who have different backgrounds but it's not common.