The point I am making here is no matter what aspect ratio monitor you use, you should always have the maximum in-game view not being limited by any black bar or stretching.
What you are saying, to put it simply = if a game is not optimized for different aspect ratios, then of course the image will be either stretched or with black bars. A prime example of this is D2, where even if you have a 16:9 monitor, you will get a stretched 4:3 image of the game on full-screen mode. So as you are saying, it will indeed fill the whole screen, but become distorted. The same goes backward if you cram 21:9 onto a 16:9 monitor, it will look like crap, but it will all be there with either black bars or stretched / distorted.
So my point still stands firmly rooted as it is a fact. If the game supports it, you will always have a bigger viewing angle in-game if you have bigger aspect ratios ie = 4:3 < 16:9 < 21:9 < higher ARs.
There are 5K+ Ultrawides which have the same pixel density as regular 4K monitors. And they are, well, wider physically. So there are some arguments to be made. But I’m not here to debate tech.
5K2K UW - https://www.msi.com/Content-Creation-Monitor/Prestige-PS341WU
There is nothing else I want to say about this, I just wanted to let the first guy know, that he is a hypocrite for saying that:
Same like saying: The problem isn’t the car, but it’s the fast traveling speed it provides.
The whole point of a wider monitor is to get a wider image.
Maybe focus on the problem, instead of the tools we use. In this case, the problem is game mechanics not functioning properly in higher resolutions + ARs. Not our monitors, keyboards, or frequencies of our CPUs, just to name a few.