Multi quote has exactly the opposite effect of what you propose in my opinion I actively hate it so why not let individual posters decide how they want to post and those who find multi quote convenient can use it and those that don't don't have to. A bit jobsworth to dictate how people can and can't post. We're not children.
It's moderating.
The same person posting 5+ times in under 2 minutes on the same page/thread is monopolising discussion. The multi quote option is there to use.
You're on a power trip here mate to be fair.
A power trip? Mate, if this is a power trip, my ambitions are tragically low.