No, not my style.
Another reason for the heat theory, is it's the only part of the wheel that's supported by a backing plate (bell on the brake disc) and shouldn't therefore be subject to any stress of this nature.
The wheel is made of alloy so should expand uniformly if it gets hot. It doesn't (or shouldn't) get that hot. No matter how hard you cane the brakes, the wheel will never be too hot to touch (i.e. less than 60 or 70C depending on how well-'ard your hands are).
If you iask yourself how you would crack the wheel at that point, if you had infinite physical strength:- you would either pull the spoke away from the hub, in either direction, or you could force a lot of weight/shock through the spoke vertically.
The first method could be replicated on the car if the wheel bolts were incorrectly fastened.. if someone tightened the bolts up with the wheel touching the ground they could have stressed the wheel, so that a pot hole or speed hump was acting in a non-uniform manner (it becomes concentrated at one point).
Does the wheel have a spigot ring? That should support the wheel at the hub.. maybe one isn't fitted..?
A heavy vertical shock in the spoke would just as likely buckle the rim as crack the wheel.. so look on the inside of the wheel to see if its buckled. The inside rim is not supported by the spoke, so more vulnerable.
Of course, the wheel may be made from a duff batch.. but wheel manufacturers (especially European ones) have all sorts of testing and quality checking they must do (by regulations) so it's hard to imagine that it is a fault (though still very possible).