Not only is IPFS not built on solid foundations, offered nothing new to the table, and is generally bad at data retention, but the "opt-in seeding" model was always a step backwards and not a good match for apps like plebbit.
The anonymous distributes filesystem model (a la Freenet/Hyphanet) where each file segment is anonymously and randomly "inserted" into the distributed filesystem is the way to go. This fixes the "seeder power" problem, as undesirable but popular content can stay highly available automatically, and unpopular but desirable content can be re-inserted/healed periodically by healers (seeders). Only both unpopular and undesirable content may fizzle out of the network, but that can only happen in the context of messaging apps/platforms if 0 people tried pull and 0 people tried to reinsert the content in question over a long period of time.
This has been discussed and experimented with to death where such networks existed for a long time. Just because you never heard of them or even knew they exist doesn't mean that they don't.
See Freenet/Hyphanet and the three approaches (local trust, shared user trust lists, web of trust) if you want to learn something. The second one worked out the best from a performance and scalability point of view compared to the third.