I haven't read of anyone on this or any other forum advocating for 30mm men's watches.
What I (and others) have expressed a desire for, is dress watches in the 36-39mm range. I have a wrist size of a bit over 7 inches, and I find 38mm (and thin) to be perfect. There are many watches at 40mm that I could wear that, to me, aren't proper dress watches as they are as wide as my Submariner.
Your mileage will certainly vary, but the one thing upon which we will agree, is to wear what works for you.