I paid for a year, but what used to be an obvious benefit is no longer that. I order some stuff, but had the same experience you did so I use orders less.

Twitch prime used to justify paying half of the cost on its own, but that no longer gives me the one benefit I care about (no ads). That leaves video, which is a good fringe benefit, but not a main need for me. Amazon music was not a replacement for Spotify (too much things gated behind another 9 usd a month paywall).

To me, it feels like they decided to slowly weaken the benefits of the overall package and hope inertia kept people from opting out (not to mention the dark patterns like cancelling subscription removes the benefits of the current subscription).