My impression of the VAX is, regardless of whether it was absolutely first at anything, it was early to have 32-bit addresses, 32-bit registers and virtual memory as we know it. You could say machines like 68k, the 80386, SPARC, ARM and such all derived from it.

There were just a lot of them. My high school had a VAX-11/730 which was a small machine you don't hear much about today. It replaced the PDP-8 that my high school had when I was in elementary school and visiting to use that machine. Using the VAX was a lot like using a Unix machine although the OS was VMS.

In southern NH in the late 1970s through mid 1980s I saw tons of DEC minicomputers, not least because Digital was based in Massachusetts next door and was selling lots to the education market. I probably saw 10 DECs for every IBM, Prime or other mini or micro.