I know this doesn't yet apply to me but in a few years time if I built a heavyweight or featherweight (i can't now or anytime seening as i don't have the funds nor the experiance) and it got smashed to pieces by a spinner then it could cost hundreds of pounds to get it repaired (if it wasn't beyond repair). I know I only have antweights at the minute (and i know that there are antweight spinners but not at RR or RL) but if spinners were aloud back then it would discourage me to build a feather or a heavy purely because of the repair cost.