If websites choose to enforce a system whereby commenters have to sign up with their verified personal details, many people may be put off and conversation rates could dwindle. This in turn may reduce traffic and said websites may suffer from it.
Some websites may choose to forgo commenting systems altogether because they may be too strapped to enforce such a system, or they may be risk-averse and wouldn't want to have their necks out anymore after this ruling.
A big problem is that a slander lawsuit may hit any time and the only things you can do to prevent it is to moderate the hell out of your UGC. That may not be feasible though. Business insurance against this kind of scenario is crazy expensive and as a business cost may be unrealistic to most. One of the people that co-run a decently sized e-commerce store in South Africa told me once that one's best bet is to have enough money on hand for a lawyer because the insurance will cripple you.
Over at http://www.mybema.com I've played around with many ways around this sort of issue. Right now, negative consumer reviews cannot be seen if you visit the site. Only the category of the review can be seen. In fact you can only see the review if you sign up and subscribe to the author. However I doubt that provides any sort of defense because legally slander is slander once another party is exposed to it. Alas, my pondering continues...
I don't know about EU or the states but in South Africa there have been rulings like the one in the article where the plaintiffs had their cases thrown out because it would be unreasonable for the media owners to moderate every comment made.
What do the other UGC platform owners on here think? How do you manage these kinds of scenarios?