One shouldn't spend 2 minutes blocking elements in a page that you would read hardly 5 minutes. That's counter productive and annoying and should be automated. An extension helps in that.
The picker creates rules that are persistent, so it would be 2 minutes over however many times you visit the site. Not too dissimilar to looking for the extension and installing it.
That's what I thought as well, but I repeatedly find myself blocking the same elements on Medium. Maybe there's some element of randomization in the ids of the offending elements, or else I'm using the extension wrong and only creating temporary rules somehow.