It’s not reasonable or practical to tell someone to ‘go and make your own instance’.
It's even less reasonable to tell someone to give up control of their instance in order to meet your desires. You aren't the one running this place, so you don't get to make the rules. The beauty of decentralization is that it's far more reasonable to tell someone to create their own Lemmy instance than it is to tell them to create their own Reddit.
Are you actually aware of the costs and difficulties in hosting alone, let alone management?
Yes, actually. I was involved in the discussions on this very topic on Pluspora, a Diaspora pod that was created as a temporary lifeboat for Google+ refugees. The cost per user for even a small fediverse server is less than $2/year, and that number gets smaller as the userbase grows. the userbase can cover that cost via GoFundMe donations or Patreon contributions, just as they do on this instance.
It’s not a viable solution for most, let alone a relatively small niche that fits into a community or two.
Short of taking control over someone else's instance, it's the most viable solution available. There's no easier way to start your own online social group than with open source decentralized social media. If you can't be bothered to do that, then abide by the social contract of the instance you're on, because it's not yours.