I have seriously considered restricting myself again to one film camera, one lens, one B&W film for one year, and taking lots of pictures.
When I only had one camera and one lens, back in the late '70s and early '80s, that is pretty much what I did - except I changed films a lot, since I was still learning what taking pictures was all about. Some of my favorite pictures are from that time period.
For someone starting out, I would recommend this restrictive approach. If you are learning photography, of course take beginner's steps. I believe once you've learned the lessons from that experience, though, it is time to move on. At this point, I've decided that one film, one camera, one lens just won't get me where I need to go.
One lens alone is too restrictive and just one camera is also too restrictive. There is no one-size-fits-all lens, and I have not yet found a one-size-fits all camera. The camera that fits in your pocket is a lousy camera for taking studio-style portraits with flash, for example.
So - control the GAS, but use what you've got to the best effect. Learning which lens, camera, and film (or settings) to use for which situation is Step 2. It is a longer step than Step 1.