If it was about LLMs then it wouldn't have to be preemptively rushed. Like, they could wait a year or two, their bank account isn't going anywhere. The users and data of big tech are the real value. By waiting a year for LLMs to take effect you evaluate properly, long term lose nothing, and don't have to go through massive hiring to compensate. It's not about LLMs.

The real reason is these companies have been overpopulated and produced basically no visible changes in 5 years. Google search is worse with auto-generated results not written by humans, YouTube has become super rabbit hole instead of discovery, Twitter shipped NFT profile pictures and Spaces.