anyone know why . ?
A CPU is hard to make and few people actually finish them. There are also the demands of life like family, health, and job which ebb and flow.
The Amiga is not as simple as you think. It took guys from Atari years and then guys from Commodore years to get anywhere with the Amiga. It took them years so why does everyone think that it can just be done with no budget and a handful of people overnight?
Commodore employed hundreds of people and then there were updates to everything they made. They made it look simple but just because they made it work doesn't mean that people today understand what they did. Some of the people Commodore hired had a math background. What kind of math background does the hobbyists re-creating Amiga have?
The fact that hobbyists in this endeavor aren't consulting past engineers from Commodore should tell you something.
Unless you have a college background in electronics, there are few people who will teach you everything. I know hobbyists who won't teach because they don't want competition from others.