Not being able to scrub video is an accessibility issue. If you don't catch something on the first watch, it's incredibly frustrating to re-watch the whole thing instead of going back a few seconds. Even if it's 'short' content. Looping the whole clip again isn't useful to someone who just wants to re-listen to one line so that they are sure they understood it correctly. In one case, a small nuisance; very frustrating in the general sense.
In the case of YouTube the extra pain is that I've trained 'double tap' a YT video for scrubbing. But what does that interaction do on a Short, in the YT app?! Like! It likes the video instead of scrubbing. On something that doesn't seem any different from a short normal YouTube video.