I think the issue is how you're uploading content. So on a reply, there's the option to attach files, located at the bottom left of the typing window and an option to "Insert other media" at the bottom right. using the one on the left adds a photo to your "My Attachments" section of your profile. (Click on your name at the top of the page, and choose My Attachments from the drop down menu.) Using the "Insert other media" option allows the user to either use one of those attachments again or post from URL like we used to do on CT.
Each user has a size limit on attachments, and once that limit is reached, one will have to be removed in order to post another one. As best I can see, the only way to do this is to go to an older post with an attachment, and edit it to remove the picture. Meanwhile I don't think there's a limit on posting an image from URL. Or at least if there is, I have not hit that limit yet.