A mixture of tribal politics and pure badness!
On the one hand you have decent Amigan's that support all of the OS flavors and if they don't then go on about their business and wont bother anyone else.
On the other hand you have the minority of bitter individuals, usually its the same names that will trawl through every related thread twisting and spitting venom as they go. 
i found a lot of the threads with Hyperion (Ben Hermans) or the Frieden brothers where I thought "Was that response really necessary?". And I do not even talk about the typcial red vs. blue battle. So they are partly certainly not innocent about the polarisation. For me personal it is not that important who uses the "Amiga" trademark finally. I would have preferred it that it would be used by the different camps (as long as it has still some recognition and thus value) because all are based on the same heritage and API. But this will not happen. So i only look at it from the outside. The faith of a platform is not decided by the trademark but by its features, hardware it runs on, price and software that is available.