Or you had some "in" at your current job that you may not have somewhere else.

I've done fine at my last two long-term jobs but I also very much got them because I knew very higher ups who answered an email right away.

It actually encourages me that a lot about the hiring system is pretty random. Otherwise the big tech employers would just skim the cream except for people who really don't want to work for those employers. As it is, there's enough randomness that lots of good people end up at other companies.