Title is misleading. This is not really an alternative to theory. Rather, it is just a slightly different approach to having fun on the guitar. At least I think its a little different. At the end of the day, its all just different ways to describe the same thing. Our resident professors of theory, @fezz parka and @davidKOS, and many others, have always been very generous and very helpful. They know way more than me. Just thought I'd toss out something that has worked for me. Rather than thinking in terms of scales and chords, I focus on intervals. Same thing, I suppose, just a different way of thinking of them. Intervals, plus ear training- I try to learn where they are on the guitar, and what they sound like in my head. That way, I hear a sound in my head that I want to make, then I can make it on the guitar. There's a successive interval, like do mi, a third, which you can think of as relating to a scale, or there's playing the do and the mi at the same time, which you can think of as a chord. I like to learn how each of them sound. And then when I want to figure out a song I say oh, that sounds a fourth, a sixth, etc. It doesn't get you all the way there, but it helps. Justin has a useful ear training course up on his channel these days for anyone whose interested. Just some food for thought on a snowy day.