The reality is that PC's address the needs of a fundamentally different market than "TiVo"s or even mobile phones. While most could, and probably should, be using secure boot noone seems to be eager to take away the option to disable it.
Microsoft perennially makes small movements in that direction. Reduced control over the OS and attempts to exert control over the software ecosystem. I assume they're still trying to push consumers towards Windows S mode devices.
Kernel mode anticheat that won't run on systems that aren't attested. Streaming platforms that won't serve up decent quality streams. Even if you don't notice the pot being boiled there are those of us that do.
Tangent: To me that sounds like a reference to the "frog boiling" story. This has been debunked [1], a healthy frog will not remain in a gradually heated pot of water. We need a better analogy for this.
Hello from 2013, and here you go!
https://wiki.ubuntu.com/ARM/SurfaceRT#Secure_Boot
https://openrt.gitbook.io/open-surfacert/common/boot-sequenc...
Plus, tablets are not PCs. People are happy with tablets and phones as locked devices. They are not happy with PCs as locked devices, and have not accepted such control, maybe outside the MacOS ecosystem.
That said, not all general purpose computing devices are useful for all things. For example: you can, but probably aren't, going to use a mobile phone for a server. On the flip side: you can use a server to do your banking, but most people won't find it as convenient as using their phone for banking (even though banking from a stationary computer is far more convenient than it was in the days when you had to go to a branch). Likewise: mobile devices can be used for content creation, but I doubt that you would find many office workers jumping at the opportunity to use them in the place of a desktop or laptop. On the other hand: someone who is on the road a lot would probably appreciate their portability.