Sure. But AIX is something you are forced to use, not something you opt-in for. All the remaining commercial Unixes are kind of in that boat.
People my age and younger just didn't get much access to commercial Unix environments when we were growing up. Once we got into industry, we found it hard to see the justification for high Unixes when we had experienced good results with low Unixes. So the low Unixes have mostly won the war. This story repeats time and time again in our industry: the freest foo conquers the non-free foo, even if the non-free foo is technically superior.
IRIX was and still is the Bugatti Veyron of operating systems. Any time there was an IRIX 6.5 upgrade, we'd throw a party because the systems were so trivial to upgrade:
In the late 1990s, when I was writing code that needed to run on an eclectic collection of platforms, the worst of them in terms of weirdness and unreliability was Unicos. Irix was probably second, and HP/UX third. As far as I recall, AIX was weird, but reliable. Solaris was solid, and Linux was pretty good, but still somewhat new at the time.
People my age and younger just didn't get much access to commercial Unix environments when we were growing up. Once we got into industry, we found it hard to see the justification for high Unixes when we had experienced good results with low Unixes. So the low Unixes have mostly won the war. This story repeats time and time again in our industry: the freest foo conquers the non-free foo, even if the non-free foo is technically superior.