This is indeed a general rule, but there are oddball cases, like when the firm I was at was acquired and the new owners kept all the back-office staff, but laid-off the developers (the acquisition was for the customer base, not the technology).
Which raises an interesting question - what's the valuable parts of Twitter? Customer base, for sure. Architecture for scalable messaging, absolutely. The rest of it? Not sure.
I'd argue that Twitter's brand is among its most valuable assets. It's globally known. Used and promoted by influencers like celebrities, artists, politicians, media, business leaders, activists. It's all over music, TV, media of all types. Heck, an entire movie was made about it.
That sort of broad public awareness is very hard for any company to get.
