Turner Kirkland (Dixie Gunworks) and Val Forget (Navy Arms) really got the ball rolling in my era (60's) with quality ML's availability, parts, and promotion of the sport. There was a lot of junk during that time, too.
Most major gun companies saw the market, upped the quality and put their names in, which, coupled with national professional advertising brought more mainstream gun guys to get involved with black powder. Colt started making "second generation" cartridge revolvers and "Commemoratives" became the new status symbol. Fun times.
Times change. People's interests change. Truly think the entertainment industry both fuels interest in historic stuff and also dampens interest. "Westerns" brought six-shooters and lever actions. "Davy Crocket" was good for Kentucky Rifles "Dirty Harry" demand for the .44 Magnum. etcl. etc. Today, it seems to be all "tactical" black plastic, etc.
Just glad to have been alive through the whole thing. In the words of Elmer Keith, "Hell, I was there."