I am hard put to defend reddit and a lot of the things they do ... but I can attest, from personal experience, that scrapers are a huge problem for anybody trying to keep a complex site working. Withholding the display of the comments will significantly reduce the database traffic needed to satisfy a request; I can see why they would want to do that for anonymous readers.
I don't understand why sites like reddit need to do any work on (unauthd) GET. They are not instant messaging platforms, they are forums. You can live with a ~1-2-5 minute delay on forums. So POSTs (from logged in users) append to a queue, and a worker does work at regular intervals, creates the HTML and that gets sent to a cache + distributed to a CDN if needed. There's no need to do work on unauthd GETs for a forum.
I personally don't like it, but hard to blame them.
Outside some Stoic altruists, this is their advantage and I'd do the same.
Agreed; we have a Linode VPS for some small WordPress websites and it was grinding to a halt after an AI crawler started iterating through every possible date in "The Events Calendar"’s URL structure, sequentially scraping calendar pages all the way back to like 1970. I'm sure that's partially my fault for not putting it behind Cloudflare or anything though.
Well Reddit would have a lot less scraper traffic if it hadn't shut down the feed API 3 years ago in an attempt to keep its data closed and only distributed to Google (which paid money for it). Self-inflicted. No sympathy.