But why would you? You can either automatically link categories using # (support), or type out a whole longform URL. The latter would make no sense. What if you typo a domain name, now the user sees an error message with no way to navigate back to the main site, whereas a typo to yoursitename.com/c/categoryname you at least have access to the navigation
I agree 100% with Richard, creating a new DNS entry and redirect every time you create a category is pretty pointless.
Those URLs are redirects, gmail.com redirects to mail.google.com and google.com/docs to docs.google.com. Many of those URLs have changed over time, so the redirects keep things neat and prevent old bookmarks from breaking. That’s very different to creating an excess of entry points from day one, and assumes that anyone creating a category now at any point down the line also has access to DNS to maintain parity. That’s a very silly assumption.
How? mail.google.com is webmail, sheets.google.com is a spreadsheet app, they’re totally different services. There’s no comparison to categories on the same app.