Nice try. Now every nostr user is obliged to have bitcoin and subsidise the miners while the relays get?

Decentralised personal and group relays are probably the best solution, you can't spam my relay, and I only hook it up with others. The word "relay" is another poor nomenclature choice. It doesn't much relay as store and forward, and it doesn't do that to the extent that say SMTP MTAs did.

The motive for this, enriching miners while they do nothing and others do the actual work looks like an indirect subsidy.

Fortunately it's not mandatory and if you choose it, all strength to your hand. Best outcome is this isn't yet-another-login-protocol kind of problem that complicates and reduces utility. Coming from the home of Electrum, that's no surprise.