Everything works if you use User-Agent switcher extension. So they went through the trouble of making an "unsupported" page and redirecting you to that page instead of doing nothing
Reddit has a lot of value, just not people who can utilize it. Anonymous nature of Reddit doesn't matter when you have Meta's cookies while accessing it. Content is also nicely categorized so they can easily push, for example, insurance and credit card ads on r/PersonalFinance. It is pretty wild that Mark Zuckerberg is the only person to figure out how to make money off of social media after more than 20 years of social media existing.
Advertisers just aren't running away from Reddit. They were never there in the first place. Reddit's revenue is tiny considering it's userbase. And their data is categorized well, by default, for free by a volunteer force of moderators. And still they're not making money. How is that even possible?