I've got a mini ITX HTPC under the telly and have done for many years. It's running a G3258, 4GB DDR3 and onboard graphics. The Virgin Media box gets more use but the HTPC gets used regularly for a number of things.
The workout videos my wife uses come through their own website and aren't streamable via the TV box. It allows us to play films we bought through Sky Store while we had a Sky contract via the Sky Store website. Sticking a webcam on top of the telly allows for a family zoom meet-up on a screen big enough for us all to see as well. It's also been used for some living room gaming through GeForce Now.
Whilst a lot of people seem to have moved on, there is still a place for HTPCs based on what you and some of the others have said.