Seen in my company
There is no old computer only bad os.
To be fair you can 100% have a PC that’s too old and/or too low speced to run Linux with certain desktops. For example I personally wouldn’t use a PC with under 8gb of ram today if I wanted to run a modern desktop and Wayland compositors basically require (or soon will) Vulkan 1.0 support (for Nvidia that’s Kepler GK110 or later, AMD GCN 1.1 or later, and Intel Broadwell or later)
The thing about Linux is that you have choice. You can put Xubuntu on a laptop with a Core 2 Duo and 4GB of RAM and it will fly.
You can absolutely keep using older X11 desktops or WMs forever, that doesn’t mean you’re getting the same experience as everyone else on a modern Wayland desktop or WM
There is a world of difference between “not getting the best experience” and “the entire computer is unusable now”.
Except if you have an old NVIDIA card. The current kernel doesn’t support the old binary drivers anymore and the nouveau drivers are slow and buggy.
