That’s because you’ve chosen an instance that is more heavily curated. You can check which instances yours has defederated from at sh.itjust.works/instances
But if you look at the same page on mander.xyz/instances my admins are only defederates from threads.net and burggit.moe, so I already experience the fediverse as you describe.
While I agree that an IPFS solution could be quite resilient, I’m not sure that the average person is willing to put up the resources or risk of hosting content. CSAM, copyright, etc, all become more of an individual risk that you’re relying on moderators to mitigate for you. (Rather than the risk going to the server hosts typically doing the moderation covering their own ass)
Additionally, while there may be decent representation of people willing to do some small amount of hosting of services (myself included) on lemmy, I think making this mandatory really limits the growth of your social media platform.
I think you could achieve what you’re looking for right now by self-hosting a private lemmy instance with signups closed, and this wouldn’t close you out of existing federating platforms.