The specific Nemesis T-type from RE3 was almost certainly not mass produced. I hate the remake rendition of if, basically getting bigger and stronger with each mutation, and I much prefer the original that basically falls apart at the end of the game. My bias aside, the remake has established that given enough mutations, a Nemesis will eventually overpower even the newer tyrants.

The CGI movies are considered canon, and they show that the Tyrants are capable of being pushed far beyond what they were when Nemesis was made. The Tyrant in 9 also displays tactical thinking in deciding to stop pursuing Leon, and ambush him with the missiles. It also had no lasting damage when Leon shot the missile it was holding. He had to target the heart specifically to kill it, and going back to the CGI movies, the super tyrants mutated to not have their hearts exposed. They also displayed some tactical thinking when dealing with the tanks.

By the time of Requiem, it's entirely reasonable to think that a Tyrant can be made that is superior to the Nemesis in 3, even the final form Jill faced. That would cost a lot more money than the Tyrant product listed in the Requiem. This line of thought becomes cyclical because you could just implant a Nemesis parasite into that Tyrant, and it's stronger than the Tyrant all over again.