I appreciate they acknowledge the nuance and shortcomings. When I first heard that baseline = available for 2.5 yrs, I felt that was a big disadvantage to users with older devices.

IMO a better solution would be a tool that scans all your HTML/CSS/JS output for keywords and features, and that returns a list of availability across browser versions. Like caniuse but scanning your whole build directory. That way devs can see for themselves what features they depend on and when they were supported, rather than relying on someone else's green stamp of approval in the docs. Does anyone know if such a tool exists?

Edit: seems like Eslint can do this?