I repeat: they have been released *in the last 20 years*. It doesnt mean they are all 20 years old. It means, DVDA and SACD have been around since 2000 or so, followed much later by BluRay music releases. So, a 20 year span of time. Some of the releases that have full range LFE are just a year or two old. Some are two decades old. Age has nothing to do with it....if that was your point.
My friend, I will repeat this. This is music (no standards) versus movies (which have standards). It was obviously the choice of the mixer to make the .1 full range, that option is there. The music industry does not have to adhere to the guidelines of the film industry, and vice versa. Based on that fact, you cannot spread what the music industry does (like peanut butter on bread) over the film industry audio mixers do. That is called conflating.
The music mixers have no real need for the LFE channel, you can put all the bass you need in the front two or three channels if they chose. The LFE channel was created for film soundtracks, not music. That frees these guys up to use that channel however they want.