Maybe if disposable keypairs were used this would be more viable.
Sharing your "main" identity with a service provider is dumb.
Discussion
I agree. Subkeys have been a thing for a while in asymmetric crypto. I don't think people value their nostr identity very much, and it shows.
Agree, there should be a child key that is derived using some public information from the service and has no visible tie to your main key.
This could be a signing service, so that you can grant and revoke access to signing in your behalf. Temporary child keys could be a way to implement this while securing your main private key.
Sounds similar to how the SQRL protocol was designed.