I'm wondering about non-resizable and non-movable modal dialogs. They seem really frustrating, especially considering that they interrupt the flow to fill a form or do a selection or whatever interaction is required. Many times I need to see some of the info underneath the modal, which is usually impossible unless I close the modal window.
I searched the site for an answer and couldn't find any. There's a relatively similar and quite old question on UX Stack Exchange Should modal dialogs be movable? with an accepted answer that says that modal dialogs shouldn't be movable and even mentions resizing. However, most of the arguments for that answer seem like arguments for actually doing the exact opposite.
Anyway, my question isn't much about if they should be resizable/movable or not, because I assume at this point it will be an opinionated question. Rather, I'd liek to know WHY is that the case other than interrupting the flow (which is interrupted anyway, so that is a non-argument).