Since you said it somewhere else and are now replying to me, I'm going to guess you're trying to personally defend these points to me rather than to Reddit in general. First, it's undeniable he commented on every single video of Ethan and Leafy and a bunch of other YouTubers in order for people to recognize him and for him to get top comment and steal viewers. That was his only purpose in commenting. Second, he wasn't stealing anything like specific lines or entire videos, he was just using their memes occasionally, using a very similar frame for when he played videos to Leafy's (admittedly common), and his format was essentially the same with the same type of humor, all while doing videos on the same things they were both doing a few days/weeks after they did theirs. Back when he did montages he copied the format of other memers and used the same exact frame and memes and etc as he's doing now. He has a history of it and numerous other YouTubers have recognized the trend, this isn't imaginary. Watch his very old videos that are done on the same source video as an Ethan or Leafy vid and that were done after H3h3 or Leafy released theirs and you will see the overwhelming similarity-- this isn't a coincidence, all of those conditions don't just naturally arise when you have a certain personality, it's very specific. The fact you're saying that anyone that says otherwise is irrelevant despite it being right there to look at shows that you aren't open to any different viewpoint on this, so I'm going to move on and stop wasting my time.
Ethan did his video without personally insulting him at all, he pointed something out everyone had already noticed and simply saying something negative about someone's channel is not a "backstab". When your friends are shitty you can say that publicly, if they can't handle being told they're shitty in a specific context on their channel and they sperg out and attack you for private conversations then that person is unstable and you should not continue to interact with them.
If you saw someone shit talking a mentally ill person or a child irl would you not condemn them? You can't expect them to just ignore videos about themselves that have hundreds of thousands of views like they don't exist-- their entire online life gets flooded with people sharing it with them and wanting them to reply. The hostility towards them would be manageable/not exist without Leafy and the type of shit you're defending. This whole "people being shitty is an innate part of the internet and if you can't handle it you shouldn't be on it" meme needs to die. There's no basis for it at all, ethics are not dead online, you are still held to a standard of behavior. Videos of mentally ill people and kids being cringeworthy are all over the internet, but other people aren't taking advantage of that because they realize the possible repercussions and the general negative nature of it. It shows that you're immature and unintelligent when you can only satirize people with very obvious faults rather than more subtle ones and probably aren't very good at creating content independent of very obvious observations.
They both said mean things in the private conversations, but I don't think Ethan did anything wrong. I don't think Leafy did anything wrong in those same convos either, but he should be blamed for publicizing their entire history of private interaction like fucking TMZ or Gawker just because Ethan said something negative about his channel that was true. They weren't best buds or anything, the messages don't go that far back, they were just acquaintances on good terms and you can tell because Leafy clearly doesn't give a shit about him in how he immediately decided he'd go for character assassination when Ethan did no such thing. You don't need to "stick up for your friends no matter what" even when you've only spoken with them for a few hours total in your life.