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.