Landscape height blending questions

So I’m trying to figure out how height blending worked, and this is not the first time I’ve asked this question. But how the fudge does it work.

Here is the part of the documentation I dont seem to understand;

So I made a fairly similar image to test:

Here is my results:

I seem to be missing something on how this should be used because I imagined this to work like this where the texture was used based on the weight;

My questions are, how do you properly use this stuff? And how do I make it stop fading. I want 100% either grass or 100% rock. It seems like it is trying to fade the alpha anyways so it look almost as ugly as without alpha… Which makes using the alpha pretty dumb. Grass and rock cant possible be on the same place, it looks fake as s***

This doesnt look like height blending, it looks like alpha blending: