I started writing this in response to @gregorypatrick comment elsewhere, but it greeeew so long and general, that I decided to change it to a full post, not to dump this wall of text there..
There is something 'hostile' there, but not about posting or publishing or discussing. First of all, downvotes are often now about "post value disagreement". Especially you can see that on posts with high 'reward' value.
Some time ago it was widely known thing that you could send cash to a bot and get it back in form of a upvote, sometimes with guaranteed 5-10-15-20% return. I probably wouldn't be wrong if I even said it was "widely accepted".
People probably got that return in mind when they bought votes for themselves. I'm not sure. Just guessing. I did that myself some time ago as well. I also thought it can get my post some extra views. Well, it did not. In fact, I doubt it got me a single viewer. (Also, after rethinking it, I could invest that STEEM in a better way, and also when I look back at those posts I can't really easily tell how much 'score'/'viewers' did my posts have, because votes from bots simply obscure that information and I have to filter that out to see the real image..)
Anyways, once this practice really boomed some time ago, it is now ... not welcomed by many. What was meant to be a promotion service, turned out to be farming service. Anyone having enough steem/sbd could post any trash and get skyrocketing upvotes from bots, and even could steadily earn some % this way, even without getting anyone to read that posts.
Of course, it had to happen that this become widely exploited. And many users grew tired of this. Some were angry seeing others earning % for posting crap, some were angry for seeing lots of crap being posted, some were angry for seeing that crap being forced to 'trending' level (just because 'trending' is taken according to post's value, not unique viewers, etc) and so on, pick your own reason. The net result is that there's now a large user group that is allergic to any sign of bid bots voting on a post, especially if the post's author is found to have bought the bot-votes themself. The free downvotes feature added recently made it even more significant. For a long time groups like SteemCleaners or SteemFlagRewards were downvoting things deemed "abusive" (plagiarism, spam, ..) or "platform-abusive" (like overusing bidbots, farming, ..), but now it's also casual readers that got into curation and that don't feel discouraged to downvote.
So, bidbots aside, you can also get downvoted simply for .. "reward disagreement". Launch steemit.com site and try downvoting something and check the popup that shows up. You can even see that phrase there in this popup. This is also encouraged by the addition of free downvotes. Downvoting still doesn't earn any curation rewards, but also if used reasonably, doesn't use up your upvoting power. Basically, if you see a post that in your opinion has too much $ on it, just downvote. That doesn't necessarily meaning "to call your friends and downvote it to zero", but just do your thing according to your sense of value. It should be normal, and noone should get fussy about, because that's why it was meant to be from the beginning..
If your post grew naturally (by other people's votes) and later this caused someone to think its "overvalued" and caused other people to downvote, it's fine. Simple disagreement in the group. Author's reward is a net effect of people's opinion, and it's great. More people on the + side, or more people on the - side, that's what scoring posts was designed to be about. No loss for the author. The author only gets more or less depending on the final opinions of the readers.
But, this makes use of bidbots MUCH less appealing - if author sends cash to a bidbot, the bidbot upvotes a post, bidbot voting formula ensures the vote is more-or-less equals (or better) than the cash sent, so they'll get their cash back, but then.. if people downvote that post, author can actually LOSE that cash, physically, because the return may be lower than the cash sent to the bots - of course, you can risk it if you like, some bidbots are still active (but keep in mind the current global mood is quite against bidbotting your own posts).
One thing left is, what if someone else buys a vote from a bot, to boost your post? Well, if it was done with positive intent of making your post more visible, that should be viewed as a fine thing. Let's say I spend 5 STEEM on a bot to upvote your post. I decided to lose 5 STEEM. If I wanted to reward you, could just transfer it to you. OK. But for some reason, I decided to announce your post as better, and decided to buy a vote from bot, so your post gets a high upvote (higher than my account could do!), so others have higher chance of seeing it, and that curators get their share, etc, etc, etc. It's positive for everybody. But other people look at it, and can disagree. If they disagree, they downvote, and the author doesn't lose anything, it was potential 5 STEEM reward from me, me who decided to not send it to you but instead to turn it into upvote, so other have a chance to disagree.
Just check out for example this post. While it probably has every reason to be promoted to a wide audience, and someone bought bot votes to boost it, it also got some serious downvotes!
If others did disagreed with my vote bought for your post, then, well, I should pick a better post to promote? Or maybe all the people downvoted because they though I am your alt-account that you used to promote your own post? Or maybe they downvoted just because they hate bidbots and farming that was happening for a long time? Who knows..
This is actually the bit that we could call 'hostile mood'.. Situation when someone buys an upvote for some post, and people immediatelly think "was it his alt-account" or "is it voting circle", isn't friendly for sure. All the more reasons to be careful with buying votes..
Also, everyone knows there are bitbots, voting trails, but then, there are also tools like this: https://steemit.com/steem/@emrebeyler/steem-downvote-explorer :)