I think it's true that depending on what speakers and headphones a production has been tested on, that'll affect which ones it also sounds best on - that's a given.
That sounds logical and is a common audiophile assumption but in practice it’s not really true. It’s true that the mix will be affected by the monitors but the monitors will typically be both “Mains” and “Near-fields”, with significantly different presentation. Productions for major artists will often have elements made in different studios and lastly (and most importantly) when the mix is finished, it will go to another studio to be mastered. If there is any colouration in the studio it was recorded/mixed that’s found it’s way into the mix, mastering will remove it, that’s the point of mastering.
But since major productions have multiple people involved and will typically be listened to on a wide variety of devices - from studio monitors, to home speakers, to monitoring/tracking headphones, to reference hifi headphones, to cheap bluetooth speakers, laptops and phones
While not impossible, it’s unlikely the mix/master will have been listened to on such a wide variety of devices. A top mastering engineer will have many years experience of carefully analysing numerous recordings on a variety of systems/room and will have tuned their own mastering studio, in combination with training/adapting their listening skills, so that they can create a master with their monitors/environment that will work well on a variety of consumer playback devices/scenarios. Some mastering engineers will do a quick check of their master with some different speakers but others don’t need to.
With headphones, it's difficult to calibrate the response so it sounds the same to multiple people. Different HRTF can cause differences in response with headphones, and headphones can vary from copy to copy quite a bit. However speakers in a room with everyone sitting behind the board in the sweet spot sound the same to everyone.
That’s a naive and somewhat incorrect view of what often happens in practice, particularly with the more major artists. Firstly, everyone does not sit behind the board, everyone is not in the sweet spot and therefore it doesn’t sound the same to everyone. But more importantly, even the sweet spot varies very significantly from studio to studio. This is particularly important because most major artists tend to favour a particular engineer/producer, will often use various different studios and that engineer or producer will have a several different clients. These freelance (“celebrity”) engineers emerged in the 1970’s with mix engineers such as Bob Clearmountain. They’re constantly flitting between different studios, often on different continents and get little time to adapt to the very significant monitoring differences between all these different studios.
The problems you mention with headphones are very real. However in practice, with most of the major artists, there are just as many problems with “speakers in a room” (or rather “rooms”).
In general you are correct, it’s not advisable to mix on headphones and in the majority or vast majority of situations experienced engineers would not choose to do so. However, a very few do choose to mix on HPs and even those who don’t, sometimes run into situations where it is the least worse option or the only viable option.
Clearly, your personal experience does not extend to these workflows/scenarios but obviously, the world is not defined by your personal experience and you cannot state that it never happens or only happens with “non-pros” simply because you personally don’t have the experience. I am a long time pro, have often flitted between numerous studios (in different countries and continents) and have on occasion mixed on HPs, even though I prefer not to and advise students/others not to. My experience alone falsifies your assertion and again, I’ve linked to an article with several top engineers who also falsify your assertion.
Hopefully this will not go the way of some other “disagreements”, where your assertion is demonstrably incorrect but you’ll defend your experience/opinion as applicable to everyone else ad infinitum.
G