I haven't seen any miracles, except for significant losses during auto-battles.
Regarding joining neutrals - imagine if, on week 3, 50 Dancers or 80 Harpooners join your side. With large armies, the chance becomes quite real, but your opponent simply didn't get lucky, or it wasn't a week for their native armies - what's the point of joining Gnomes when your opponent is also a Gnome and has a real chance to join even more?