In addition to the advantage of explicitly specified capabilities mentioned by others, I'd say a userscript is also much more durable and low-maintenance than a Chrome extension. This is coming from someone who's written an extension for personal use before, and had to jump through a million hoops with Chrome Dev just to give the browser permission to run my own code that I wrote myself, and that's to say nothing of the whole mess with manifest v3 as well. Throughout the entire time I've been able to happily keep using userscripts written by myself or others with 0 maintenance required.
for me on chrome (stable), all that’s needed to install my own extensions is enable Developer Mode in chrome://extensions, then load an unpacked folder as an extension
It's been a while since I've had to do this so I'd be very happy to hear if the process has become smoother since - does it no longer give you a big warning that you've got a dangerous unpacked extension installed every time you start chrome then?
