> The problem with flex is that it means "adjacent" elements can randomly wrap anywhere even if they really belong close to each other, whereas with grid I could arrange for closeness separately for each available horizontal size.

I don't put down a flex and leave it at that; I use media queries to change it between flex-horizontal and flex-vertical. This means that I either wrap at particular width for desktop, or "wrap" at every cell for mobile.

Granted, it's not perfect as it only supports two classes of screen size - desktop or mobile :-)