We're from the same generation and I also loved heavy metal... I learned about new bands by buying magazines specializing in metal, renting videos from the big

We're from the same generation and I also loved heavy metal... I learned about new bands by buying magazines specializing in metal, renting videos from the big bands which usually would include opening acts with new bands (or even the famous guys or their fans on the video wearing other bands' t-shirts), from friends, by going to festivals (there were lots of them around if you were willing to travel around a bit, though I was in a highly populated area so that may not have been an option for you)... there was always more bands that I knew about than what I could possibly listen and buy albums... of course, today it's so much easier, but I feel like the problem today is actually the abundance of choice! You could just listen to the best couple of songs of each band, and still have more than enough music to enjoy. That seems to be what happens if you let Spotify or other services pick songs for you. You can still dig in if you really want, but I feel like most people won't do that... and you start having very high expectations from what a good song is as you only listen to effectively, the "greatest hits"!