Ok, here's the long-ass complete history (for fans who weren't around).

Ventgrumps (Rantgrumps was a rebrand) was formed in this small period of time where r/gamegrumps still wasn't a hugbox, but was in a period where people were trying to be more positive than usual and was a little more moderated.

Why?

Ok so the grumps, and especially Arin, have had an uneasy relationship with this subreddit since the Jon era. In one Jon era episode he said he didn't like r/gg because they would talk shit about suzy (and that was the Jon era, she wasn't even a part of GG then, she was just a goose)

So during windwaker, the sub gets super toxic about Arin "blaming the game" (go back and watch windwaker, that was so overblown), Arin see's this and makes a post called "Imma say words" explaining how he feels bad for this. Around this same time Arin and the grumps make sort of a coventant with the sub that they'll make an effort to interact more, and they did, as a result mods removed some of the vitriol to keep this going. It was sort of like when you had to clean the house because you were having company over as a kid and you didn't want people to see the shit your siblings smeared all over the walls.

In this period, Ventgrumps forms, under the argument "constructive criticism" (read: incoherent screeching) wasn't allowed. So they made their own sub. And it was arguably more toxic than Rantgrumps is. Some of the first posts were talking shit on suzys makeup and was getting upvoted. And when people pointed out the blatent misogyny they were like "nuh uh" but eventually the mods caved and removed it. It was a safe space for anything negative about the grumps, even if it was super terrible and deserved downvotes.

Eventually the Suzy etsy scandal happens on the main sub and Arin is basically like "ok, fuck this subreddit forever" and the more attentive moderation falls away.

But Ventgrumps stuck around, eventually for whatever reason I guess the mods quit and they made Rantgrumps, in spite of things on the sub basically returning to normal, if not more negative than before. And even though any time Arin get's into hot water for any reason they all come to this sub and get upvoted for saying well...anything negative about Arin. Including calling him a worthless has-been on his own fansubreddit but still act like their the oppressed ones because they want to just be around people that completely agree with them no matter how nonsensical all day.

TLDR: when that sub started, years ago, it atleast kind of made sense because the sub modded a little more heavy, but it has just no excuse now