As a web dev, I fully agree with this, but with a huge exception: clickable text. Anything that is meant to be read as content should absolutely, without fail, be selectable and copyable (assuming appropriate permissions). But stuff like tab headers, buttons, or even text-sparse tiles - things meant for the user to click on - can, and usually should , prevent text selection. It is super annoying to be clicking back a…
It's always bothered me that links on webpages are single click to open. They should require double clicking to open (like just about everything else on a computer) and single click should be used to start selecting text, like everywhere else on a computer.
That is some Windows UI stuff, If I recall correctly in OSX you don't double click as much.