I assume it's not against GitHub terms, but I find it inappropriate and unfitting. Smells like marketing for discoverability with no content, just forwarding. Which is a thing of course, but if you're asking me as a developer and personally, I'd prefer the project not do that. A repo as a pure landing page uses nothing of what makes a repo a repo.
If it's a developer creating their portfolio and linking their distributed projects to their developer profile, I think I can see some value in that. But in that case, all of them should be in one repo.