All of their early micros were hobbled in some way to make them not-quite-compatible; the Rainbow, despite running MS-DOS, was not IBM PC compatible, and the Professional series had incompatibilities with standard PDP-11 systems. The Rainbow didn't even include a FORMAT command for formatting floppy disks; you were expected to buy preformatted ones from DEC, and using standard 5.25" floppies with hub rings was a good way to kill your floppy drive due to the RX50's mechanical design.
Probably the best shot at a home PDP-11 came via Heathkit with the H11 and H11A machines, but that was a small niche.
Even when they finally admitted to themselves that micros were the way of the future, they concentrated on the enterprise market, to the exclusion of all else. Back when the Alpha was the performance king, I would have loved to be able to have one, but the cost was well out of reach of mere mortals.