And contrary to your beliefs it was even harder to do in 1985 because there was more competition. Commodore had to fight Apple, Atari, IBM, HP etc etc, each one trying to impose their architecture over the other on a limited marketplace (the personal computer market was smaller at that time).
For someone in the know you should learn a bit more about the history of the personal computer before making such remark.
I think you have a rather odd view of computer history.
Back then computers were much more limited so it was possible to do something revolutionary with a relatively small numbers of people and relatively small amount of money. Doing the same today - if it could even be done - would cost Billions (not millions) and require an army of highly qualified people.
As for competition being less, you are kidding? right?
You'll be going up against a massive installed base of pretty much one one highly entrenched system. It's much, much easier to go up against multiple systems in an immature market.
You're basically talking about developing a chipset significantly better than AMD/ATI or Nvidia could develop and producing an OS that would then easily sweep aside Windows - as well as the rest of the PC industry.
You really think that today would be easier than doing it in 1985?
To put it into perspective, the leading PC architecture in 1984 was the Commodore 64.