It's not because they're "immature" or anything like that, and it's not a diss on anyone who still likes them, it's just that I tried to watch a new video of theirs and it just didn't hit me like it used to.
It's similar to what happened with me and the Nostalgia Critic (Tho admittedly with significant differences): I was a pretty big fan early on and for several years, but over time just fell off, started watching them more sporadically, before kinda just not keeping up with the new stuff anymore.
Was just thinking about them and Nostalgia Critic (also, CinemaSins and a crapload of gaming youtubers). this used to depress me but I've accepted that my tastes will change over time.
Though, if there's one youtuber who has only grown my attention and interest over the last near-decade, it's Jim Fucking Sterling Son.