What do you mean "of course"? If I publish a book on DTRPG I can sell it any number of other places. DMsGuild serves a single purpose: access to non-open D&D content.Well, of course not. That doesn't mean you can't republish the unique IP in it somewhere else, though.
Also, what "unique IP" do you think you will be repurposing elsewhere? You can't use DMsGuild to publish your own setting, and anything you create for a D&D setting is embedded with their IP.