The question is, though, what constitutes strictly necessary cookies in which use case. It also isn't clearly stated anywhere - or otherwise agreed upon, in which way you have to inform your users about these cookies.
Hence, many website providers opt for the legally-safest, but terrible in terms of UX, alternative of displaying a cookie banner.
Case in point: the very website we're using right now. While it's true that Hacker News would be possible without cookies, for commenting and voting you'd then have to log in each time your browser session has been closed, which would make for a less than optimal user experience.
But I'd honestly argue that your view of cookies is very conservative.
Why is the user experience less than optimal? Why can't the browser remember your credentials and automatically sign you on? (It could, of course - e.g. using client-side certificates!).
We should also ask ourselves whether the user experience on some website (which lasts seconds, and is mostly irrelevant) is more important than the privacy of its users, which will be impacted forever (through first-party data collection, third-party data collection and sharing / resale of data).
It's very easy: Just don't use any cookies. You can still serve text, images, videos, anything. It just works, you don't need a cookie notice, your pages are faster, and you even save money on hosting static content.