For now, the cost of excluding a high-paying txn is relatively small, and the virtue signal is comparatively strong. Maybe when fees account for 90% of miner revenue the desire to discriminate will be reduced.

Subsidies tend to distort all kinds of markets. How can blockspace be properly valued if empty blocks still pay 80% as well as full blocks?

Today, Ocean delays the inclusion of "spam" which might be tolerable to the market, after all, how quickly do you really need your JPEG stored on everyone's node?

The market for blockspace also permits a miner to censor non-spam and prioritize these "spam" transactions instead. If the market wants spam txns confirmed quickly, then all it takes is one pool (or an alliance of pools) with similar hashrate as Ocean to effectively negate all their efforts to delay spam.