Fun fact: if you're a miner and set your minimum relay fee to something higher than usual, like 10sats/vByte, it's pretty much the same thing as mining with full-rbf from a double spend perspective, as you'll reject the first lower fee tx in a spend/double-spend combo.

When mempool pressure is high this even happens naturally, as the mempool is limited in size, and when it bumps up against that limit low fee txs are dropped.