I'll concur with that statment, but realisticly, I don't believe for a minute it is about "ankle support" - realisticly most of us with a tendancy to turn ankles (myself included) just need a shoe that offers some lateral stability - boots do thie with a wide sole, so do most trailrunners with a nice wide grip that doesn't make it easy to "roll over" on them.

I do very nicely in a pair of Montrail Hardrocks, I don't tend to go over on them even though they offer no "ankle support".

To some extent, I'd even say because I "know" I'm in lighter shoe, and I am aware of it and think with the brain a little more.
The other possibility is that when I'm in the light trailrunner, I know if I get into goo, my feet are just gonna get wet, so I don't end up doing acrobatics and little bits of trail ballet and triple sowkows just to not get the feet wet. So some extent it's a lot safer to just walk through it.

I have done long, very rough trails (west coast trail on vancouver island) successfully in trailrunners.