afaict three reasons:

1. OCEAN uses a payout system that's similar to PPLNS which has relatively high payout variance relative to PPS/FPPS (which small pools can't provide because it's very risky/expensive), and big miners want less variance all things being equal
2. To mine on OCEAN, you also have to run a bitcoin node so that you can build templates (which is a good thing), but more friction = less customers
3. The pool is relatively young and network effects are in play

OCEAN is virtue signaling and hiding that miners who spamfilter are free riding on miners who don't. anti-censorship, but not anti spam, is the future of bitcoin:

#978118