You're not the first to discover this

Ivo shaved off a 2k norton a few years ago and posted about it here, and I've shaved off my 1k Shapton a couple of times now with different razors and I vaguely remember reading about others doing it over the years.
I figured as much
So yep, the 1k shapton and the 2k Norton will produce a sharp edge that will shave ok, which provides some confirmation for what Verhoeven saw in his electron microscope - edges reach their maximum sharpness with surprisingly low (to me) abrasives, after that all that happens is the bevel gets smoother and the consistency improves.
Our discussion over at B&B is what prompted me to actually go for it, I have done the 4k a few times
And yes the confidence in the strokes is also a major factor. I think confidence probably has as much to do with the improvements we associate with experience as technique does. I doubt that many novices could do the same thing as you did until they had a few months to a year of experience under their belt.
In total agreement, I wonder how it would have been if I had done proper prep and great lather too...
One fun experiment to do is to take a razor and hone it up and shave with it ever day, sticking with it day after day as it slowly degrades, until it's not fun to shave with anymore. Then oil it and put it away and go back to your normal routine for a few weeks to re-acclimate your senses, then try that old razor again. You'll be amazed at what you were managing to shave with all those weeks, and helps explain some of those old stories about guys going 20 years without honing or even stropping. It's amazing what you can get used to...