i think a big part of it is that their audience isn't just other gamedevs, it includes gamers

those gamers often have strong emotional attachments to games/characters that very few people have for google sheets

studios get crazy backlash for nerfs and other changes, so i can see not wanting to attach your name and face to that. in the other direction, i wouldn't want a horde of gamers using my words as evidence that my employer is dogshit, unless that was the goal of my message

The IP and that the industry is very big-release centric. Even the engine you are working with is often news, people monitor and report on job listings for this kind of thing. It's obvious and uninteresting that a slightly updated new version of google sheets will release probably like every day, and they will be virtually indistinguishable from the previous ones. If literally anything you say about your work on GTA6 is news for the next N years, you don't post anything. The few non-indie devs I see publically online are usually for live-service companies like riot.

I have seen game devs that are public with what company they work for also get death threats/hatred/etc whenever a game comes out that flops even if they didn't work on it specifically. Gamers can come off as a really political audience with a lot of grift money to be made on culture war stuff so it makes sense if you're an apolitical gamedev to stfu.

Its because of crazy gamers online

If you even mention the game/studio you work for they might come at you

I've noticed the same for many industries across the website. There don't seem to be requisite psychological safety for experts to speak up there, unlike with many forums of 00s or even other modern and current public social media.

I work for an unnamed AAA developer..

...and people I work with have gotten mail on their PERSONAL phones, addresses and social media accounts because a, let's say "enthusiastic", fan found out they work on a product they have strong feelings on.