Worst idea I have heard in a long time.
All that will happen is anyone who is being punished for being a twat will report everyone else for everything until everyone has to pay more, no way can they keep this all monitored without some kind of community rep system which is more representative of the dicks you play with than the person themselves.
Not going to work and if they implement this I am out, so many people will be driven away from Steam it will ruin them.
Also, this means it's now impossible to vent when you need it. Absolutely no one will stay calm and unoffensive for 100% of their gaming career, everyone will be punished at some point.
On top of this, what about people who only play singleplayer, do they instantly get free games since they can't offend anyone?
Valve you absolute asshats, the system we have now is not broken, don't try to fix it with your cock handed shit.