Actually, I don't read that many "hate posts" about Sweden. Each year there is a country which gets blamed for being overrated.
I remember people were brassed off when Dima Bilan was winning the contest in 2008. In the 2000s, Eastern European countries were often overrated, culminating in said win of Russia. That was the era were people were annoyed, losing interest in Eurovision, that's why the juries were created. Russia was (and still is) one of the main scapegoats in Eurovision, partly because of their political interventions, partly because they tried to gather the "Eastern fan block" though sending soulless disco pop with short skirts. Often undeserved they climbed up high in the rankings and believe me, I've read much worse postings about Russia than Sweden.
In the early 2010s, it was Azerbaijan's turn, drawing critisism for pushing their entries to the top, buying votes, taunting other countries, getting undeserved good placings in the finals. I also read a lot of bad comments on this topics.
And if you look in the comment section of some Greek or Turkish or Macedonian entries on YouTube, then you have seen the real Eurovision hell, the edge of good and bad. THOSE are comments I would never like to read again, very hateful and insulting.
Now it's Sweden's and Australia's turn, being the "scapegoat" of the late 2010's. I'm telling you what, guys: there will be better times again. You are not hated. But after every rise there is a fall and especially Sweden has been hyped the past ten years a lot, justifiably but also wrongfully. They polarize and of course they will attract a lot of schadenfreude, as well as Russia did when they didn't qualify, as well as different countries for some reason. Also Germany had to deal with many not so nice comments about our poor song choices the past years but the critics were right. Sweden's time will come again because I'm sure Sweden has the quality to send another smash hit like Euphoria (which I'm not even liking much, by the way, but I'm acknowledging its victory for different reasons).
I myself have always talked openly about my opinions on different songs. I've always written about strong dislikes or hates of songs but also countries when it comes to things I didn't like in Eurovision, may it be the organization or anything else. That doesn't mean I hate any country. It's just about Eurovision. People have to learn to distinguish.