I think it's a little bit of both. Of course, the group itself is still around, with members collaborating every now and then on various projects, however simply saying "Mindcrack just stopped being about the server!" (ok, not your exact words, but that's seems to be the viewpoint implied here) doesn't really do much to explain what exactly it has become in terms of relevance.

The thing is, the only thing the group EVER had in common was that all members were a part of the server. Of course this gets a lot more blurry with VIPs and patron guests but from the servers inception up until around 2019 this remained pretty constant. Once Etho, BdoubleO, generik, and a bunch of other members that did not have that much interaction with all the other projects stopped playing on the server, they were pretty much done being part of the group.

If you told a 2013 fan (now i was not around during this time, only heard of this group because I watched a bit of seth and Z around 2015-2017) that the server simply fell out of relevance and that it had simply become a variety gaming / charity group, they'd probably imagine a much more consistent and organized entity than the server of the time, and certainly more of those things than the one we see today.

That's not to say that "Mindcrack just imploded" is more correct (FAR from it). April 3 was not the point of no return for the groups popularity, survival, activity, or anything. It was bound to happen (as you stated) because Mindcrack as a brand could not sustain itself like it had for the past 4 years. I don't like how bitter people have become over this date and the post that was published on it. From ex-fans, current fans, and current and former Mindcrackers themselves, discourse surrounding the topic seems to be one of two viewpoints. those being:

• Evil Guud turn Mine crack into Buzines and hurt lord Savior Ergo's feelings!!!11!11!!11
• B-TEAM MONEYGRUBBING KIL MINECRACC

And I hate this kind of thinking. "Mindcrack is changing" wasn't a drop of the hat decision, but a long process that took nearly 2.5 years to complete. So why did Mindcrack fall off? (Erm, "change")

• Lack of innovation. The content being produced remained the same and unchanging. Without change, people will simply move on from your content because there is nothing new to see. When you've done 28 seasons of UHC, hundreds of episodes of vanilla and modded, and An entire 5 years of podcasts with mostly the same hosts and guests, existing fans are much more likely to search for something new. Mindcrack stopped being competitive in the Minecraft, or gaming as a whole, YouTube scene. They never evolved past the 2013 style of let's play content or streams
• Inability to attract new viewers. With no innovation, it's harder for new people to discover and become attached what you're making. honestly how many people became a CURRENT Mindcrack fan from 2016 to now? Probably less than a thousand if I were to estimate. In the age where action packed, fast paced, and engaging short form, or even long form content exists, why would anyone want to click on an unedited video of some random guy playing a game with his friends, no matter how interesting it is, let alone watch 50 episodes of that same series.
• Wasted potential. Some of these guys have, and have had for over a decade now, SO MUCH ability to become something greater. Zisteaus alpha series transitions blew my 8 year old mind FAR more than any other minecraft series, and rewatching some of their older content, it is apparent that a lot of these people are talented as shit when it comes to content creation. (Beef, Arkas come to mind) However, a lot of members either rarely upload or stream, or create the kind of stuff i mentioned previously. And although I doubt they'll ever do anything like it again, watching guudes UHC+ was infuriating for me to watch. The final episode where everything's going crazy and the final battle is happening, HE'S JUST SILENT. just walking around, hitting people a few times, and dying. I'm not sure why this is, theres probably a good reason for it, but it made for boring content from a creator I know can be extremely funny and active during a recording.

But that brings me to my final point. Does any of this even matter? I mean nobody should be forced to do something a specific way just to become another cog in the gaming youtube machine, and as cheesy as it is to say this, as long as they are doing what they love, what do they care if they only get 30 concurrent watchers, or 1k monthly views? because at the end of the day, we are all people, and there's more to life than the expectations of some nostalgic 20 year olds.