The hashpower a miner produces and pool accumulates is verifiable, thusly, over the x-axis one can calculate their average number of blocks to consistently represent their percentage of network power. It's unlikely to change much inside the 2-week difficulty adjustment window The tx's we're presumably talking about are enormous tx's, and may originate from a sanctioned country, or entity looking for privacy, or an entity looking to lock in an advertised mempool rate months into the future. Otherwise there's no guarantee this tx will be confirmed in any reasonable amount of time even with an RBF