I do a lot of scraping at my day job, and I agree the times we need to use a headless browser are very rare. Vast majority of the time you can either find an API or JSON endpoint, or scrape the JS contained in the returned SSR document to get what you want.
This, at least subreddits are relatively stable, public and searchable. There is so much knowledge hidden inside huge chat logs of semi-public Discord servers which might disappear at any minute and is hard to retrieve, unless that server maintains a wiki or something similiar.