Why are miners not abandoning those pools?
Discussion
This is so wrong in so many ways and very much reminds me of a particular Chinese mining hardware manufacturer who thought (a few years ago) that mining empty Bitcoin blocks (to leech block rewards) is ok just because its possible.
If the default mempool does not include the highest bidding transactions (due to standardness rules limiting size), it makes sense for a miner to accept these transactions out of band in order to maximize the fees from the blocks they create.