It's weird to think that there's are entire Cyrillic, Chinese, and Spanish internets out there that are practically invisible to us in the anglosphere. I wonder what their versions of Facebook, Twitter, Youtube, Reddit, and Hackernews are...
For instance, Discord isn't being crawled, Instagram and Twitter tend to be very annoying about having to create an account with them.
Reddit (and HN) have a separate issue in that they fundamentally violate netiquette by locking threads and preventing necroposting even WHEN it's what should be done (also in case of Reddit, frequently (ab)using shadowbans).