The only place I actually encountered this was at a defense contractor where if you did not have clearance, and they didn't happen to have uncleared work ready to staff, then if they wanted to hire you, they'd have to have you do nothing for 6 months while your clearance went through. All other companies I've worked at (including FAANGs) have always had 3-10X more unstaffed work than they could possibly do with their current staff and always had something for new people to onboard into. We'd be constantly giving leadership the bad news: "We'd love to do projects A-G, but only have enough people to do A, B and maybe C."