Many websites use JS that is slow and jumpy -- bloated -- on a phone, especially a cheaper one like I use.

Also, I like to use Chrome on my phone, so installing an adblocker is a lot of work for little benefit. It would slow down the already laggy rendering and require I either use a different browser or let an app intercept network traffic.

I'm perfectly happy not using JS (or for that matter, media) on my phone.