I'm curious which companies you talk about, because there are a lot of statistics that many of these companies have significant higher R&D spending than most big corporations (certainly more than many famous SV companies). I also know of two people who joined one of these companies one came from a research postdoc position and made it to head of R&D (like a vice president I guess) within 5 years, another came from a slightly higher level, but also quickly made it to a similar position.