Other sites allow this, but too often in the past it has been used for nefarious purposes, mostly for artists to make their gallery noticed by others. There are legitimate ways of doing this within the Critique Corner, so if you want more comments, please go to that forum.
If you are caught double-posting or bumping your gallery, you will first receive a post or PM from a moderator requesting you to stop. If you continue these actions, you will be warned 10%. Member Artists are liable to have their artist-statuses revoked, while upper-ranked artists could face demotion and/or being placed on the promotion blacklist.
It's really frustrating that I even have to make an announcement like this because it is one of TDA's oldest rules, not to mention that making such posts in your gallery is entirely nonsensical. If you see anyone doing this, please report them to the moderators.