I've worked in almost all of big tech, and these companies don't create mandate just because "Trust me bro" or to gain some "political achievements". Their are teams who champion new technology/languages, they create proof of what new technology will bring to the table which cannot be filled with existing ones. I left amazon 7 years ago so don't know about recent development. However at Meta/Google teams are encouraged to choose from the mandate languages and if they can't they need to request for exemption and justify the exception.