filters work (Core w/ PR28408 compared to mempool-space today ). What nodes choose to pass on to peers is none of anyone's business, nodes have always been able to come into consensus despite not sharing policy.
spam ad nauseum aside, nodes hear about transactions at different times by design and it shouldnt be expected that nodes must relay the same transactions either.
the detriment to block propagation from a network with diverse policy has always been on the nodes which choose to propagate junk that others do not. Seeeing how there's no requirement that other nodes must participate in propagating compact blocks, the best course of action for the nefarious actors is to mine the blocks first (or pay someone to do it for them -oob-). Forcing this behaviour isn't a centralizing force to miners, it's normal incentives; if they want to push their luck, go for it. Nodes have all the reason to utilize any tools to make their odds suck a little harder.
when I see that mempool-space is so different than my own instance, im reminded of clicking through block explorers back in 2016 when mining pools were stuffing transactions to fill up blocks jacking up fee rates for years. "I should take running a node more seriously"
