Not ridiculous at all. If you use the service that pays the artists below the value, you are endorsing that underpayment. You're literally voting with your wallet that underpaying the artists is fine.
Pirating doesn't support the artists, but it's also not weakening their expected rights for future business contracts, which supporting services like Spotify does; after all, if all these other artists are getting paid 'x' much, and all these consumers think this is what it's worth, how is anyone but Beyonce or Swift or Kanye gonna have any hope of arguing against that?
There is no way to inform Spotify that you don't endorse their business practices, except to not subscribe. Subscribing is an endorsement.
Personally, I purchase my music individually on iTunes (and download and convert to mp3). Apple still takes a cut, but it's much lower than the near-100% cut that streaming services take.