Sniping is fine when it's obvious the previous group isn't continuing the project. I remember a lot of groups self-exiling themselves, because they were pissed off at people offering alternative translations or edited versions of their own, sometimes without crediting the original team. It can be annoying for active scanlation groups when someone's release takes priority over yours, because then it's like your effort didn't matter as much, especially if someone is paying your group. And let's not forget that sniping has a bad rep because trolls do like making MTLs of the last few chapters of a manga. The block feature for a group exists for a reason. Sniping isn't a net positive or something to keep scanlation teams in check. It's just an action that requires context.
But then you also have other instances, like that one time back on Batoto where a scanlation group was pissed off at someone offering (while crediting) an edited version that erased the satirical side notes the scanlation group was putting throughout the pages. That same scanlation group threw a hissy fit and said it was their right to do what they want with the translations, like they own them. The manga itself wasn't that great, and sometimes those notes were hilarious, but there were definitely people annoyed that the scanlation group put these notes throughout the manga. Usually people reserve the jokes for after the chapter is done. And there's the cases where the scanlation group does not care as long as the plot is explained, but will put all sorts of memes for dialogue, and the comments find all this hilarious.