I am new here, but I’ve noticed that downvoting on this site tends to be quite virulent with respect to off-topic questions or questions which probably are poorly formulated.
Off-topic questions are downvoted to a.) decrease their visibility on the front page (-8 is needed for that), and b.) allow regular users to start voting to delete them. (needs a score of -3 to avoid a 48 hour waiting period)
Questions tagged feature-request get downvotes/upvotes depending on whether people agree or disagree with the proposed change. Should (and could) we require the tour badge (and/or rep) to give answers?, for example, is such a feature-request.
This also happens sometimes on questions tagged discussion. People that don't have the time to write an answer signal their agreement or disagreement with the premises in the question by using their up/downvotes.
There is something to say about not using your votes for (dis)agreement on questions tagged discussion, but to judge them by their merit: Is this a useful discussion to have? Have we had this discussion many times before, did the person putting this up for discussion do their research effort? Is the discussion clearly written, is it clear what we should discuss?
Looking at your examples, On which site is it easier to earn reputation? and Is downvoting a well-written question by a beginner OK? might well have gotten downvotes for being not a very useful discussion (easiest to get rep) or something that has been discussed over, and over, and over (downvotes).
Then there are questions tagged support, they usually get downvotes for 'lacking research effort'. In other words, the downvotes usually mean 'you could've known this if you spent a few minutes trying to understand how the site works'. I guess those are the ones that I'd like to see a bit less downvoted: If there's no duplicate, or the info is not easily found... Having those downvoted a lot seems/feels unfair.
What I don’t understand is the aggressive attitude of this site...
Downvotes aren't aggressive. They're meant to filter content, have good discussions rise to the top, and the questions that are unclear, lack research effort or are unuseful to the bottom/off the front page. Please don't ever take them personally.