I notice this especially with my Norwegian learning. People are rude, call me names, or make fun of me on Reddit for using the wrong word or “en” vs “et” or using a direct translation because I don’t know how they say it in Norwegian, like saying somethng like «Ingen av bedriften din!» instead of «Dette er ikke din sak» (according to the casual version of Bing Translate) whereas a Norwegian-speaking Fediverse member would just say something like “You’re doing good, but it’s actually _____.”
Probably just the law of large userbases. The more people around, the more rude people there are likely to be. Rude people are always a minority, but they tend to be more vocal.
A large portion of fediverse users have abandoned Reddit for moral or ethical reasons. So while occasionally people will be rude here, it tends to skew more towards polite discussion.
Large userbases, and the “somebody is wrong on the internet” effect. If we like something we see we’ll possibly like/upvote it and move on with our life, if we see a problem we’re far more likely to jump on and interact. So a hundred people might read something and be neutral towards it, and it’s enough to have one asshole react poorly to ruin the mood completely.
The same dynamic works for reply guys, and sadly the fediverse is in no way immune. But hopefully there are more people on here who are aware that it’s a community building exercise, and who make an effort to leave a positive footprint. :)