I think this post misses a bit the “why” of stateless Ethereum. Stateless exists because we can get cheap consensus nodes. I can instantly spin up a node on my laptop, even if it doesn’t have a fancy SSD. An Eth2 validator after the merge, potentially running on a lowly Raspberry Pi, can hop on the Eth1 shard, validate one block, and forget about it for 100 blocks, and then validate another block. This is why statelessness matters.
Wouldn’t any stateless proposal include adding witnesses to gossiped transactions? Stateless clients should absolutely be able to participate in gossiping.
It is obvious that a stateless node can’t answer questions about the state. That was never the goal. A stateless node exists to maintain consensus, and nodes that answer questions about the state will still exist in order to, for example, save JSON-RPC data.