Noticed that. It used to be easy to bypass, because old.reddit.com allowed me to go there with a VPN, but they recently patched it. I found that changing the user agent to make it look like you're on Chrome and Windows, alongside with US/Canada VPNs tend to get around this, but it isn't very reliable.
Stealth used to work for a while, but not anymore either.
They are doing it to stop scrappers scrapers and punishing people who use a VPN is just a bonus to them.
It's a tool that basically pretends to be a user, it opens the website just like you and i other users do. It collects the data (images text videos) just by browsing around.
They used to be prolific, but the problem is that they use a lot of resources on the website's end. Instead big website owners started offering public APIs which allow bots to collect data without taxing the server too much