the basic difference between the apple community and the amiga community was that there was always apple as company leading the development and thus forcing the developer and user to go with them. Would Commodore have survived the same would have been the case for amiga. There would some form of AmigaOS (however it today would look like), no MorphOS or AROS. 68k would propably only existing as emulation (if ever) because they would have changed the hardware. Chipsets propably would not exist anymore. It would be a different machine today. But that did not happen, AROS is the oldest OS, MorphOS was started in the late 90s, there were the last 68k updates around 2000. That was the first split in NG and 68k. Then AmigaInc. decided to do their own "official" OS and the PPC platform started to divide too. I think what I read was that at the beginning both AmigaOS and MorphOS were running on classic hardware supporting PPC accellerators but both supporting different standards. I read discussions that this would destroy the last remainders of the market. Then arguments between Ben H. and MorphOS teams started and escalated with Ben H. claiming that MorphOS (and AROS) are illegal using 3.1. sources. And since then we have our current situation. All are using different (closed) standards and different components and are different on API level. But it is how it is.
When I have summarized something wrong be free to correct me. That is what i read in different sources.
IMO it came down to one thing-they all wanted to make the biggest buck...and it started with Amiga International not wanting to pay what 3rd parties wanted to paid for having their software included in OS 3.5- MUI I believe was the first choice GUI, but deemed too expensive by Amiga Tech, so we got Reaction (a tarted up Class Act). The included TCP stack apparantly wasn't paid as agreed, but included anyway.
Then H&P claimed they didn't get paid in full for OS 3.9 so that was another dispute.
phase5 were the only ones that actually got a PPC working on the Amiga, and wanted control of both the hardware and the software. To me it looked like H&P saw it as a Microsoft opportunity-bugger the hardware, its the software that matters and they wanted to be the ones to control the PPC OS. Hence the first split on the ppc market.
If they actually worked together and pooled their resources then things may have been better-but in the end it was all about MONEY and GREED. I wonder if any of them have actually made anywhere near enough money to at least cover their time. I doubt it.