While it is correct that placing the camera against the wall with the flip screen out like that works, you forget that your body is in the way. You cannot see the screen on the right side of the camera.
Any position in which you can stand and look through the angle finder, you can see the LCD. It rotates through 360° just like the angle finder. Your eye would be ~10 cm further away.
I’ve used the articulating screen for interior real estate photography, with no issues. Mirrors are always tricky, I find the TS-E 17 useful for that, to shift the camera out of the frame.
I’ve used the articulating LCD in settings where using the VF even with the angle finder would be impossible, such as long exposure waterfall shots in winter, where the only access is by snowshoe and the shot is taken standing on meters of powder, with the only possible platform for the tripod legs being the snowshoes attached to my feet (I suspect that’s an example of being even more constrained by the positioning of a tripod than you’ve experienced).
I just wanted to find out if any other photographers have the same problem or if we are unique in this.
Well, you’re not unique but there doesn’t seem to be a large group of CR members jumping on the bandwagon.
The angle finders were niche products even before the advent of live view and articulated screens. At this point, I suspect Canon sees no need for a new one in their catalog.
Regardless, thanks for posting this – I'm going to sell my 1D X in the near future, and this reminded me that I should offload my Angle Finder C as well, since it's not compatible with any Canon MILCs.