OK, this text takes a lot more reading than this ...
First of all, it does not cover temporary licence. So excludes nearly all subscription based games. WoW accounts might not be covered, nor any similar sub based EULAs.
Second question is digital software distribution. One can transfer (sell) a permanent licence to another person, but the software itself might be responsibility of the seller.
Thirdly, there is no need for Steam and similar systems to implement tools for sale of licences. All they are required to do to fulfill this ruling is to allow people to transfer licences between accounts. As far as I know, that is already something they can do through support process.