Reddit habit is hard to break.

https://lemmy.ml/post/1218000

It doesn't help the fact that depending of the question, every single answer ends up being only on reddit and nowhere else.
This is one of the problems for me. I frequently search tech issues and more often than not, a lot of links are from Reddit.
Really specific issues are more often than not only found in reddit, and that's not even all, for me at least; a lot of those answers in reddit are short and to the point. Sometimes you search for the solution of a problem and find posts on websites filled with irrelevant information that you don't really have the time/patience to read. . .

I'm worried, not all but large enough group of Reddit users are already deleting their account, and with that are gone years of knowledge and good answer threads using the tool that retroactively edits your comments.

They have their full right, of course, but it will be a net loss for the future.

There will be archives made available by various groups I'm sure. And that's assuming Reddit doesn't just go undelete all those. Either way I'd guess that certain subreddits/communities will end up finding their new home here or elsewhere and over time the information that shows up on reddit will become more and more stale
If you delete an account now, all the threads it ever commented on will lose context and become useless unless archived already. That's the situation we're in, people are deleting their accounts without thinking about all the content that they have contributed to and destroying it.