I wont speak for baraatje (because Im not him) but yes, mappers and players wont always have the same viewpoint - because mappers have more insight over those, that have never touched the editor before.
You see, we're not only mappers, we're players as well. We play the game (most people every day) and we like to create maps/content for it. In order to improve our content, we have to make sure that what we create is good and fun to play.
-> If we have a relaxing song, then we map a slow/relaxing map.
-> If we have a DnB song, then we can be more creative with many triplets, streams etc.
-> If we have a strong and high BPM song, then we can go crazy, have difficult patterns and create a challenge to the player.
-> If we have a song that is streamy, then we'll map streams.
-> If we have a song that sounds jumpy, then we'll map jumps.
Now, what if there's a slow/relaxing part in the strong and high BPM song (Image Material for example). What should we do? As we know by now, the slow part should be mapped accordingly, so we cant just smash streams into violin sections. That wouldnt be good design.
Skipping forward, we now have a strong and fast AR10 map with a slow section for the slow part of the music. Problem is, that the AR still gives some kind of illusion of speed and "it's still pretty damn fast" to us, even though the part is supposed and mapped to be slow.
This is where the AR change could kick in. It'd make these kinds of things much better and more enjoyable as a whole. There wouldnt be any need to tone the AR of your map down just because half of the song works better in AR8 as compared to AR9.
To you, yes, you might have the opinion that you want difficult maps to be difficult, but no, your point doesnt make too much sense in this case