Kinda needs to be default. I mean, I’m a privacy buff, and I don’t care if you know my raw specs if I’m telling you how a game runs in a public forum. Because without the specs, that information is worthless.

I'm against sharing privacy information by default. This has to be opt-in. Also a review without specs is not worthless. All the years I found the reviews without specs still helpful in Steam. Having specs gives a little bit information, especially important when you want to understand some performance or compatibility issues. But most reviews don't need that.

I don't care about benchmarks; I care about compatibility and errors. The specs that would matter to me would be things like CPU architecture, which team made the GPU, and which Linux distro they're running. Maybe number of monitors/resolution/framerate/use of freesync or framegen, too, since that can affect glitches.

I don’t care if you know my raw specs if I’m telling you how a game runs in a public forum

It may not be harmful by itself, but combined with other information it can definitely help identify you to your account. It could easily be the final piece of information that enabled you to be doxxed.

Loss of privacy is cumulative, like radiation.

Brainstorming: maybe make it mandatory only when a review is about performance of the game, because that's when it's relevant. Maybe a checkbox as you're writing a negative review that's something like 'what aspect(s) of the game don't you like', and if 'performance' is checked, a little addendum that says 'your specs will be added to the review to give context'. In that case, people who want to look through reviews would also be able to filter by those same 'types' of reviews, or see what percentage of negative reviews are due to performance, or other things. Could be a good addition overall.

But generally, if someone wants to write a bad review because of shitty controls, or plot, or the game being too short for its price, etc., there's no need to have specs attached to that kind of review.