Upvoting! I have been known to be quite offensive myself, when the situation calls for it. Although I think you are slightly incorrect - what you described seems to me to be more of a “shitpost”:
a deliberately provocative or off-topic comment posted on social media, typically in order to upset others or distract from the main conversation.
Shitposting can be great fun, if everyone recognizes it for what it is, e.g. if it is literally in the name of the community, which importantly can be blocked if the user does not want to see it. It seems mostly harmless to me? Well, within reason - it has no place in a community meant for serious discussions, and I routinely block people who do not read the room and interrupt what was intended to be a more thoughtful discussion (typically I have gone through their recent post histories and only do so when it is a repeated pattern, i.e. distinguishing b/t people who never add value to any discussion vs. a one-off comment that happens to be irrelevant) - but in a meme community it can be light-hearted, good-natured fun?
Whereas trolling absolutely crosses a line, getting into territory of intentionally wanting to cause emotional harm, examples include outright insults (“you are stpupid” (sic) rather than “I believe that you might be missing some facts and here is why…”) and other forms of literal abusiveness. I suppose there are exceptions - like that RoastMe sub where people would literally ask for it - but you know what I mean: consent should matter? Except to them, it does not:-(.
it just wastes all of our time. I’m not here on Lemmy to engage with babies that need a spanking - or… want one I guess? - I am here to enjoy myself! :-P So I block them, at which point they make new alt accounts to get around all the people blocking them, and the cycle continues. Though if there is an influx of like a hundred thousand of them, even if buried amidst a million non-trolls, it would radically change the very identity of the Fediverse, making it much more like Reddit (gag), and we would lose the ability to have conversations like… well, this one!:-D
I agree that not everything has to be “nice”, though we do need to presume that the other side is willing to engage respectfully, or else there is no basis for a conversation. On that note, I am guessing that you have not been to Reddit lately - it really is full of actual, full-on trolls there now, after the protests. Ironically the situation is reversed 100% from what it was in the past: instead of the mods blocking the trolls, now the troll-scabs block the former mods who have been booted from their subs:-(.