No, you’re missing the point.

As filtering becomes increasingly common, more and more transactions will go out of band.

So what do mining pools do? They’ll invest in building private transaction rails, and it becomes commoditized over time, so prices will plummet, long term. So there’s no deterrent to what you consider “spam.”

And now the public mempool is dead, fee estimation is basically impossible, and people submit their transactions (even financial-only transactions) directly to miners instead of using the mempool.