I did not know about reader mode. It seems that it is unavailable for some websites, so it can still be useful to switch off JavaScript in those cases.
A lot of paywalls disappear when you turn off javascript. I use a plugin that adds a button to quickly toggle javascript for specific web pages. It works for a large percentage of paywalled articles. On the few paywalled sites where I actually use javascript, it is easy to just turn it back on again when needed. The plugin I use is JavaScript Switcher, but there are others out there.
I did not know about reader mode. It seems that it is unavailable for some websites, so it can still be useful to switch off JavaScript in those cases.