Why do some forks and frames have brake rotor size limits?

AMuzi wrote:

snip

Yes, we've previously discussed the advantages of mounting a
disc caliper on the front of the fork. IMHO manufacturers
don't want to dance with troubles from fastener or caliper
mount failure, preferring to load the caliper down against
the blade rather than pulling away from it (home and XMart
installation being what it is).


Thanks Andrew. That explanation for the status quo makes some sense.