As somebody who did plenty of scraping for his own little projects, lets just say that reddit their security concerns are just PR for "we do not want to keep supporting old.reddit".

While yes, you can not simply scrap new reddit as easily as a pure html scraper is cheaper to run. And while the new reddit its js "slow down" scraping as it need to run over a headless browser. Do you slow scraping down a lot?

No. Because you can simply spin up more instances and route over more proxies. Given the fact that you can scrap millions of pages per day, on a single cheap 1 CPU node...

The limiting factor for scraping a website is not html vs js / client vs headless browser. Its avoiding detection by running from different ips, faking browser information and masking your traffic to not give off the smell of automatization (and avoiding tls fingerprinting).

I wrote this type of stuff before we had AI to help write it, in a few days time. Now with a LLM at your fingertips in a few hours, you will have a complete working version with cloaking build in.

And the larger size difference does not matter, you can block irrelevant files via faked cache responds, to give the server the impression that your a repeat client, and no need to flood your browser instance with images, fonts etc. Some think that this is a defense, aka throttling you with increased bandwidth usage lol

So in my personal opinion, its not about dealing with scrapers, but trying to push people to new reddit, so they can finally phase out old reddit.

PS: So much fun reading new reddit on your phone browser, to have it pop-up a "use our app" banner, that prevents you from interacting with the website anymore. And even blocks firefox its scroll ability (and thus accessing to the browser its nav bar). Tip for people: delete the sites cookies and cache regularly, to prevent this usage tracking, so the banner newer shows.