>Absence of button not a "technological measure"

No, but the various technological measures that Google uses to make it difficult to download a user copy of the video file, to the point where the compilation and use of an external tool is the easiest option, definitely are.

Seriously, youtube makes it more of a pain in the ass to download a plain video file than basically any other site on the web. You can't just view-source and get it, and you can't even nab the file from the event timeline like you can most sites that obfuscate that.

Like it or not, youtube-dl is popular in part because it does circumvent a lot of measures that youtube intentionally puts in place.