It kills a lot of autoplay videos, popups -- the "in page" variety -- and other dark patterns I see on a lot of sites. The only regret I have is that ads get disabled too so if it's a place I really enjoy a lot and they have a means to donate, I give them something.
Besides this, it also gets rid of a lot of ad tracking without having to install any plugins specifically to block it. I'm a big fan of using existing features, both in software and hardware, to their fullest before extending them.
But the biggest reason is my computer is a bit slow too and I don't want to spend hundreds more just to consume text; something that hasn't changed since the dawn of the web and something I've been doing for years. It's wasteful to pollute my closet and a landfill in the future with e-waste because single-page apps and fancy transitions don't work properly.