>All our accounts will eventually be linked by our writing style.

I don't think this is true for most people. Unless you are a relatively prolific (probably top 1% or even 0.1% or less), you likely do not have enough long form writing online to create a unique style fingerprint. All of your accounts will be consistent with having been written by the same person, but absent other information, will not be enough on their own to say that they were written by one and only one person.

And even for people who do have enough writing online to create a truly unique fingerprint, that fingerprint will not be universally applicable to all their accounts (at least not solely by writing style*). Even when you have a truly unique profile for someones writing style, a given writing sample needs to be greater than some minimum length in order to consistently match it.

Linking literally all of your online accounts will probably use writing style as a factor, but I very much doubt it will ever be enough on it's own.

You don't need much long-form writing for your idiolect to be identifiable. I recently returned to Reddit after a break and see that people generally don't write very long comments now, except for the autistic and others who can't follow social cues. But I already noticed that my short comments occasionally use turns of phrase that are fairly peculiar to me. Should be possible for a social media giant or nation-scale actor to deanonymize me. And some people give themselves away by outright posting in country or city subreddits.