The Altos were not official, supported products, but R&D projects and prototypes. I heard several were given away. The "real" products were the Star series.

Those didn't succeed because they were far too expensive. As were the Altos, BTW. A working system could easily run into the US$ 100K range, with workstation and printer.

A couple years later, Apple made the same mistake with the Lisa, pricing it over US$ 10K. They only got something with the US$ 2K-range Macintoshes. And those really caught on when Apple launched their laser printer.

Because Xerox considered they could never make a product out of PARC's output (Apple and Microsoft disagreed). None of it ever became actual products, it was either research material or stuff for some unis.

Also, maybe price. This was in the late 70s to early 80s, the hardware in the box was significant, the rest of the world was still running on 80x25 text displays if that.