In a group of friends, who know each other well, misunderstandings are rarer. Not nonexistent, but rarer, and the person who doesn't understand is usually willing to say something like "I didn't understand that--did you mean this? Or that?" and a fruitful discussion may ensue. But online, where the entire world may walk into the conversation (and you have no idea what their background knowledge is, or their personality, or whatever) the stage is set for massive problems. Some hearer/readers think they know what was said/written, and what meaning the speaker/writer intended to convey. In fact, they're sure they know, and they're sure how far that meaning can be extended. ("I don't like strawberry ice-cream" could end up being interpreted as an attack on strawberry growers. No, I'm not kidding. Agricultural interests are very sensitive about any perceived criticism of their crop/livestock and readily extend it from the simple "I don't like strawberry ice-cream" to "You're against strawberries because (list of made-up reasons.)"
It is impossible for a speaker/writer to convey accurate information (beyond 2 + 2 in base 10 = 4) , let alone opinion, to everyone in the same utterance/text, because of the highly variable nature of hearers/readers online...and the certainty of so many that they know what was meant when, in fact, did not have the right Sekrit Decoder Ring for that speech/text, but thought they did. You can be careful. You can work over a comment, comment reply, initial post over and over, considering every person you think *likely* to read it, and yet someone will not only get it wrong, but boldly announce that you meant something quite different from what you did mean, and then other people will jump on that bandwagon (some without even reading the original.)
I try not to be that listener/reader. Sometimes I probably am, because most of us, in some situations, think we know more about someone else's thought processes than we do. But having been slammed all my life by those who did not grasp the point I was trying to make, I do try to avoid assuming I understand when I may not.