I think there's no firm conclusion on the mechanism that causes a finer edge on a stone where the slurry has been worked a while, but the conclusion that the silica particles aren't breaking down is firm.

I think they dull. I think they're too durable to be friable and just break apart, but the edges get dulled just like an ice cube would get dulled if it was rolled around on a rink for a while. We don't get significant pressure on any one particle on the stone when we hone. It's no surprise that the binder would break down, it's soft and friable, otherwise it wouldn't let go of particles.

Did any of the blog entries show particles before and after? I think that would pretty easily show that the particles aren't shrinking. My own supposition above is just by the fact that microscopes have been around for a long time, but I've never seen a picture of slurry before and after where the after is crushed in general and very small.

I'm agnostic on what's actually happening, as long as the razor is getting sharp. There are some old wives tales in japanese stones and tools. A friend of mine who has gotten me some rare stuff tool wise from tokyo mentioned that one of the carpenters he met a few decades ago told him that if his chisels touched a synthetic stone (even medium and finish stones) that they would be irrepairably damaged and would have to be thrown away.