And in fairness, even on most cars the indicators are washed out by brake lights, certainly at some distance. What nobody seems to be able to explain, however, is the scenario in which you've applied your brake lights and the presence or absence of indicators has any effect on the behaviour of the driver behind. For sure, if somebody hit's their brakes I don't carry on driving at the same speed towards them, whether they are indicating or not. This quite aside the fact that as a motorcyclist especially you should be learning to apply your indicators in good time ahead of braking.
I can think of scenarios where as a motorcyclist I'm using engine braking to slow down so have tapped the rear brake to warn the driver behind, but I don't drag on the brake continually. Genuinely don't understand what the issue with the rear multi clusters is.
I get that some may believe that they get more people pulling out on them due to the amber lights, even though Honda have used this system for years and regardless of the bike you ride you'll get idiots pulling out on you. But the rears?
Who knows?
it's down to how you drive and perceive threats and actions