Yes, it is prevented legally. When a journal agrees to publish your work they require you to sign over copyright to them. The terms may vary on the transfer of

Yes, it is prevented legally. When a journal agrees to publish your work they require you to sign over copyright to them. The terms may vary on the transfer of copyright, but in general you are not authorized to self-host a free version of your article. You can sometimes pay the journal a significant amount of money to make it open access to the public. Some authors, myself included, ignore the agreement and still host free copies.