Long-term members of the forum who are active in answering questions and particularly in sometimes voting to close or down-voting questions or answers that seem poor are -- in my overwhelming experience --
highly mindful that many, indeed most, questions here come from learners -- it would be astonishing if that were not so (the point of a question is that you don't know or understand something or need advice)
not trying to be or seem unpleasant -- indeed posts or posters showing unpleasantness tend to disappear one way or another.
The key fact, however, is that Cross Validated, like any other part of Stack Exchange, is not a help line or discussion forum. It is designed to be a repository of good, answered questions. So there is qualified intolerance of poor questions and poor answers that is, quite frankly, in the best long-term interests of most users.
The counter-example is to imagine infinite tolerance that indulges an attitude of "this is my question, so I have a right to post it and for it not to be down-voted, edited or removed". That is just not how Stack Exchange works generally. If you want that model, there are other ways to express it on the internet.
CV is untidy enough, partly because too few people check for existing answers and because so few people (me too!) lack the time and inclination to look through older threads to try to clean up a bit. The paradox -- except it's not a contradiction -- is that greater tolerance would just lead to a site littered with junk, with many useless threads -- and in total a site that would be harder to use and less helpful. If that's what you want, try any social medium.
There are plenty of checks and balances here. For example, even as a user with some reputation my votes need to be matched by others, my edits are reversible, my powers of deletion don't even include everything I post, and I too am subject to down-voting, moderator action, and other censures. That is how it should be.
Also, if a particular decision seems too harsh, it can usually be revisited. Even moderators are the first to admit that their decisions are sometimes wrong; there can be down-voting for bad reasons; and so forth. The answer is not to raise a generalised complaint of our being "too harsh"; it is to raise particular bad decisions that you think you see.
There are many threads here about down-voting. I don't particularly want to open all that up again, but simply
down-voting is allowed here with enough reputation (some people with enough reputation never or rarely down-vote and that's entirely their choice); that is the SE model
there are explicit grounds for down-voting
no-one else knows the particular reasons why anyone down-votes unless they leave a comment explaining why (like I suspect many other long-term users I've experienced seemingly random drive-by down-votes which can only be guessed at as some kind of spitefulness).