It's a part of the ecosystem, and is, AFAICT, saying "tabs are not welcome here". Happy to be proven wrong.
In a nutshell, what you're currently using is the stage 1 compiler, aka the bootstrapping compiler to compile the official zig compiler going forward. zig fmt is opinionated because it was only meant to enforce formatting for the zig project. At that stage of the project's life, they felt it was more important to get shit done in a consistent manner w/ the people that are actually contributing than to cater to a hypothetical accessibility-impaired developer that isn't.
Zig is a very ambitious project. Prioritizing pragmatism over ideology is a fairly common theme with it currently. Another example: they repeatedly break stdlib APIs because catering to a larger audience is currently less important than getting other things nailed down first.
Right now you might be more worried about how the current compiler can't even compile Zig correctly before worrying about what stylistic choices it can handle. I'm a tabs guy myself but it's really quite irrelevant at the moment - the focus is still on figuring out how Zig should work and making that happen not day to day usability of the current toolsets for end users.
So yes, all of the quotes and conclusions you found are either old or wrong according to the very pages you linked. No, it doesn't need to be updated (or prioritized?) as they all conclude with supporting tabs you just hadn't read all of what you're citing.
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If there is still any doubt for some reason rather than trolling through GitHub issues from 2017 I'd recommend sticking to the current FAQ from 2021 which has a section dedicated to this question: https://github.com/ziglang/zig/wiki/FAQ#why-does-zig-force-m... as this is the fully current and authoritative answer on the status of tab support, regardless of where bits of past discussion lay on the matter.