In all large companies the people involved in an interview are a tiny fraction of the whole workforce.
Most of the time it's people from the team that is hiring and one or two "guests" from other teams (but usually working in the same building).
Managers also have plenty of power to influence the decision, therefore keeping a very uniform hiring bar is really difficult. (But no, it's not "completely arbitrary")
Also, I wrote that the bar dropped a lot, to the point of shifting all employees level up by one, but this does not mean that the company hires 90% of the candidates.
If a team was hiring 1 candidate every 1000 screened resumes and now it's 1 in 100 it's a whopping 10x change... but that doesn't make you a terrible engineer!
