are they

As opposed to what, having a candy bar? Give a point of reference, please.

It's funny that no one replied before I edited the substance away from my post, but anyways: many other discussions about the graphics options are full of replies that defend the rerelease's promise of "high resolution" support, saying that the game would otherwise be the size of a postage stamp or be stretched to hell (hehe). My question is, how does that explain the seemingly ineffective refresh rate options and the more obviously useless windowed mode option? The game runs at 20fps even if I select the 144hz option or if I set a fixed fps in rivatuner, and it still runs fullscreen with black bars in windowed mode.

The program only paints a screen image every so often. It doesn't matter if you have a 144hz refresh rate... if you do, you'll simply be painting the same image for ~7 frames consecutively each time.

These are issues with how Diablo 1 rendered its display. Think of it as a mosaic of tiles. The tiles are pixelated, and no matter how sharply you view those tiles, they won't create an image which isn't pixelated. (They'd have to replace the original graphics tiles with higher-resolution ones to do so.) And the program updates the "tiles" every 1/20 of a second or so. So, no matter how fast you refresh your display, you still only see a new frame that often.

I'm running the new version on a 1920x1080x144hz display. It looks exactly like it did back in the day. However, the "original" game doesn't look right, unless I do a lot of hoop-jumping to get it to behave correctly. It's stretched to 16:9... whereas the "tile set" is designed to look right at 4:3. I get pallet issues. And so forth.

LOLd at this. If you set a window to be the size of your whole screen, then it will obviously cover your whole screen. Set it to be a size smaller than your whole screen, and it won't fill your whole screen.

There is no help for you if you cannot understand upscaling support, aspect ratios, and why this game has a sub 60 limited frame rate.
Hey guys, why does stop motion look so janky on my 144hz monitor? Plz help.

this is not the case for me on a win 10, my win 7 rig displays at 1920x 1080, nice and big, on my win 10, it doesnt matter the screen I choose, it stays as a square box with black bars oneither sde and makes zero visual difference regardless of te scale I choose, its like its locked at 640.

DevilutionX has upscaling build in, please give it a try:
https://github.com/diasurgical/devilutionX/releases

thats all I got.

why I can't attach screenshot?

Did you try posting it to https://pasteboard.co and then just put a link for it here?

New account can't post URLs either without workarounds (remove the protocol portion or add a quote to the post). Images need to be less than 500000 bytes and the extension should be lower case.

Now do everyone a favor and fix your avatar.

Nice, though I think I will use my regular one (I applied it but don't see it yet), since I don't what to seem to speak for the whole team on the project :)