> A company like Digital could have made the PDP-11 into 'the PC'

They did! I kind of want one of these PDP-11 based PCs:

1977: https://en.wikipedia.org/wiki/Heathkit_H11

1982: https://en.wikipedia.org/wiki/DEC_Professional

I know of course, I'm love DEC history. But of course DEC Professional wasn't full compatible and cost far to much to be a Personal Computer. They closed down the bus also. It was more designed as Professional work station. And of course the famously released it with Rainbow and Decmade II. DEC had already lost by then.

Heathkit H11 was an opportunity but of course never followed up with.