I worked on a large web scraper for several years and JavaScript almost never needs to be executed. The only times I've had were to extract obfuscated links that are revealed by some bit twiddling code, specific to each request, and this was achievable by forking out to deno.
I think javascript comes up because cloudflare use some kind of javascript challenge as part of the DDOS protection. There are python libraries that know how to deal with it, or you can use some level of headless browser.
https://github.com/VeNoMouS/cloudscraper
