"But...how hard is it to cut it down to real bare-bones staff"

I'm sure you'd lay off the right people but it's much much more difficult than you think because everyone appears to be doing stuff. Let's say 3/4 people need to go - reviewing that individually is a nightmare for morale and very time consuming.

It also never seems to happen - instead companies take the easier road and keep doing a small minimal amount of layoffs because the big one is almost impossible and might lead to whole pieces of the site stopping working.

While it is probably the sanest objective in terms of "let's be real and honest about it", 120M or even ten time that is not going to cut it with their current situation as a tech unicorn getting to the end of their ride and trying to stop their valuation from melting.

For reference, They were still valued in the 30+ billions range mid-2015, and now barely hold above 10B.