Danny I think we should discuss this in Graduates Club, because there are some very strong points for good mono compatibility. I find the experienced producers are still concerned with mono compatibility e.g. sasha, Enrico Sangiuliano and the likes.
I really don't mean to sound like a hater but a lot of the commercial EDM that hits the top of beatport charts are not the most experienced engineers and probably don't give mono compatibility or any of the more advanced engineering topics much thought.
I think it is quite rare for anybody to listen to things in true stereo, even if a club is set up in stereo, unless you are in the very small sweet spot you are not receiving any of the benefits of stereo, iPhone's and bluetooth speakers are mono, TVs might as well be mono since the speakers are so close together, plus you would need to be sitting in the sweet spot, same for the car, you are further to one side.
There is an argument for earbuds/headphones, which are used a lot to listen to music but again, it is not true stereo, as something panned to hard left you are only hearing in the left ear, in the real world you would also hear it in the right ear a little quieter and with attenuated high frequencies. But I agree you still get the perceived effects of stereo here.
I honestly think, it is only the studio, when you are in the sweet spot you are getting the real benefits of a stereo mix.
I have done a lot of research into this, as I got obsessed with mono compatibility a few years ago and would love to discuss it further, if anyone is interested of course.
Ultimately, in my opinion, I think a stereo mix that sounds great in mono also sounds great in stereo but a stereo mix with no concern about mono will sound bad in mono.