I could not disagree more. It may be distracting to you, but that does not mean it is distracting to everyone.
When I was learning to ride a geared bike on London roads with only a C.B.T. on a scooter for experience* there was a lot I was trying to keep track of in my head. Probably true for a lot of people their first time. Clutch, watch that traffic light, throttle, down gear, car at junction, throttle, mirror!, clutch. Did I forget anything? Each a separate step one after the other, carefully considered and processed. Could easily have got one of them wrong, which was it?
When you know what you are doing everything is automatic and all of those steps happen virtually at the same moment. But with just my thoughts it is easy to overthink everything, which is distracting. For me. When I tried a Lidl bluetooth set and put on music it made a huge difference. The music occupied the part of my brain that was obsessing over the mechanics, freeing up the other part of my brain to just get on with the riding instead of trying to analyze those thoughts. It increased my attention.
In more attention demanding situations, such as urban ones with constant hazards and poor visibility, I find that whatever is playing just gets lost in background noise and I do not "hear" it. And sometimes as background noise it is annoying and I turn if off. I am not much of a filterer, but I always turn it off when doing that.
Which is not to mention that a G.P.S. in your ear keeps your eye on the road and not a screen. (Although if possible, position it near a mirror and you can check both in one glance.) And trying to remember routes, if you shun a G.P.S., is also distracting.
My favourite thing is riding on a summer day while listening to Test Match special. Quite often I find myself waiting for the score because the road needed my complete concentration that I missed a passage of play. There has never been a time that when the two conflicted, that road has not taken as much attention as it demanded. And in 2018 with the final day of that Headingley test, I made sure to stop in the first lay-by I could find when coming home to stop and listen to the conclusion. I am not sure if I was more worried it would take my attention off the road, or the road would take my attention off the cricket!
Music, or cricket, can help stop the mind wandering and losing concentration. Which can easily happen on long open boring sections of road. I find silence and thinking about what to have for tea to be far more distracting.
Every situation is different, everyone person is different. The mind processes different things in different ways, and can do several things at once. You cannot make single declarative rules of what it right or wrong for everyone all the time.
* In hindsight I should have insisted on a bike when they said a scooter would be better. They were the experts and I had no basis to doubt them.