For me it was the confluence of two events. I'm afraid I became a convert ust a wee bit before Ritter's revelation. Like, maybe 15 years or so..?
1) I got the Avalon Hill board wargame PanzerBlitz for my 13th birthday. Gosh how I wanted that game. Had seen it in the store, read the back cover ("Russian tank commanders slam shut the hatches on their dreaded T-34s ... and there -- topping the rise! ... a glint of dawn reflecting off of the muzzle of the first German tank ... PanzerBlitz is about to begin!" Oooh MY

). Showed it to my mother, made sure she knew that I wanted
exactly that game, had to have it. So for my birthday, there is was. Oooh yes! Then I opened it up, and that great big box with all those cool words and images on it had nothing but little cardboard squares inside? Are you kidding me?!!
2) I was at my local hobby shop, which had a fantastic choice of models and Rocco Mini-Tanks, and which I had patronized almost every Saturday of my life for years already, and I was looking at a 1/35th Tamiya JagdPanther, and the guy behind the counter saw what I was looking at and said "Good choice. 88mm gun, and 'A' frontal armor. The JagdTiger is even better -- it's got a 122mm gun". And I said "Uh, it was a 128mm gun, and what do you mean by 'A' armor?" And he started telling me about WRG's Armor and Infantry rules, and wargaming with micro-armor, and recommended me to another hobby shop across town that carried them (the local shop didn't).
So I went to that other shop, and saw those little tanks, and started buying them like mad! Not for micro-armor wargaming, but because they were just PERFECT to replace the little cardboard squares in my PanzerBlitz game! Oooh sweet! I still have the T-34s and T-34-85s that I bought at that time -- no tread pattering, no boxes or gas tanks, came in a clear hard-plastic snap-shut box with red foam to mark it as a Red Army tank (Germans came with gray foam, Americans with green foam).
Of course I eventually did get the WRG Armor and Infantry rules (first edition, 1972 printing). And PanzerBlitz has been in the closet ever since.