How about this one:
Current situation where blocks are getting full from artificial 1MB cap:
Attacker: large miners like f2pool
Attack: spam network from one of its wallets to another. Drive up overall fees of regular users.
Success: 100%
Sustainable for only until the cumulative the fees equals their net worth, i.e. unsustainable.
F2pool is paying the spam to itself.
How can it spam the network when the blocks it can create are capped to 1MB? It might as well charge 0 txn fees to itself. That wouldn't affect the fees of other regular users whose transactions can appear on blocks created by the other miners.
If you are arguing that centralization of mining can create a monopoly on fees, then yes I agree. But that is true regardless of block size.
It would help if you would at least think before posting. Most of what you post is incorrect.