Right, yes, that's sadly accurate. There in fact never is an image - not on the server side. It's only the browser that creates it.

I think it might be possible to render it server-side - MTGNexus manages it somehow. So this is at least possible. And I have sometimes wanted it myself... when I was creating the FICG Equestria Girls set to playtest on Cockatrice I throw together a little script to go through the Visual Spoiler screengrabbing each card and saving it out as a named image onto the local hard drive. I ought to be able to provide some way for anyone to do that.

I don't think I'm going to provide a way to link to those images though. I'd probably need to step up the amount I pay my hosting servers to let MagicMultiverse serve that much bandwidth.

It is possible to render it server side, perhaps by using the same part of the software that renders it on the web browser (I have seen things containing automated screenshots of HTML documents before, so I would think that it is probably possible).

Rendering on the client side is also possible. This seems to be the element(s) with the ".cardborder" CSS selector. If a browser extension can make screenshots based on CSS selectors, whether or not they are in view, then this can help, I suppose. (I don't know if there is any.)

An alternative is to use external programs to render the cards However, MSE doesn't import (unless they changed that recently and I am unaware), and TeXnicard doesn't currently include any rendering templates for Magic: the Gathering.