I want the forum to remain a place where there is open discussion and one where upvotes and attention are tied to argument quality and usefulness. I suspect that seeing people's names doesn't help foster open discussion and agnostic use of attention, though I have no concrete evidence or analysis to provide.
There are also different options for how to anonymize. It could be an optional add on, It could be hidden text that unhides when you click, it could only anonymize posts that are presenting arguments, etc. We could also just run a week of anonymization and see how it goes.
One last point is that if it is an issue of getting credit for your work, we could still all have accounts with our names that include all of our comments, but you would have to click directly on profiles to see what comments/posts they have made.
Interested to hear if people feel similarly or a steel-man for why names are important/why anonymization would be harmful.
Summary: Doing this in practice is literally almost possible.
The goals of having the EA Forum be a platform with open discussion and arguments evaluated based on quality and usefulness with impartiality to whoever wrote them can only be achieved by other means.
It's not a matter of steelmanning why it might be harmful. I would be okay with anonymizing all user accounts on the EA Forum too but it's not a matter of opinion because any attempt to do so is practically guaranteed to fail. The EA Forum serves other necessary functions that are (considered) just as important.
Every EA-affiliated organization or project uses the EA Forum for public communications and requests for feedback, fundraisers, job postings and quarterly/annual reports. There is no way all that content can be posted on the EA Forum without most of the authors being identified based on them being a staff member for whichever organization any post is about.
If everyone stopped publishing all of those kinds of posts on the EA Forum, there would be almost no content on the EA Forum. Discussions and arguments on the EA Forum are almost all related to posts whose authors can't be anonymized on both the EA Forum and even other websites.