i'd argue that 95%+ of users (creators and viewers) couldn't care less about downloading videos. creators use youtube because it's where the viewers and money are, viewers use youtube because it's where all the content is. none of them are going to jump ship if yt-dlp dies.

also, one could assume that the remaining 5% are either watching with vlc/mpv/etc or running an adblocker. so it's not like google is going to lose ad revenue by breaking downloaders like yt-dlp. grandparent comment (legacy smart TV support) is the much more likely explanation

It's not the 95% you're concerned about, it's the 1%, or 0.0001%, who are top content creators, who both archive their own production and use YT as a research tool themselves (whether simple "reply videos" or something more substantive). Ultimately Google will kill the goose and lose the eggs.

Those creators are what drive the the bulk of viewers to the platform.

Though, come to think of it, as YT's become increasingly obnoxious to use (the native Web client is utterly intolerable, front-ends such as Invidious are increasingly fragile/broken, yt-dlp is as TFA notes becoming bogged down in greater dependencies) I simply find myself watching (or as my preference generally is, listening) to far less from the platform.

I may be well ahead of the pack, but others may reach similar conclusions in 5--10 years. Or when a less-annoying alternative clearly presents itself.