[70rd]

There's a tradeoff between decentralization and throughput. In the extreme, only people owning entire datacenters could operate a full 'node' that would be processing 1 000 000 TPS.

Slowness is not the mechanism, ETH had ~13 second block times before the merge. Bitcoin is slow because the difficulty is targeting longer block times, not because of inherent need for slowness. Difficulty is only required so that adverserial agents (with less than 51% of hashpower) can't rewrite the chain and change transactions.