Yes we did, the major impediment was the price of available compilers, their dependency on UNIX workstations, where the Ada compiler was extra, on top of C and C++ that were already there.

Until Ada Core offered GNAT to the community, there were no affordable compilers.

Yet, there is still enough business to keep 6 compiler vendors selling them.

There were schools of computer science, accredited universities, that taught it heavily (one of the 3 lab intro to programming languages next to c++ and python, and allowed to be used through the entire program at mine). A 1/3 of graduates of some of these places got jobs in it, because they were reliable and well paying jobs.

And then the industry swapped to C++. This was not a DoD mandate, this was companies like boeing trying to pay their engineers 1/3 to 1/2 less by paying for C++ devs (starting salary for ada devs was 90-140k, starting salary for c++ devs was 60-180k according to exit statistics). They of course eventually learned that good C++ devs are actually more expensive than their old Ada ones. Not that they bothered to hire good c++ devs.

No it wasn't that nobody wanted to learn it, it's that back then Ada developers cost a lot more than C++ developers and businesses didn't want to pay them.