IMO posting paywalled sites to a news aggregator detracts from the experience of using the aggregator for anyone who doesn't subscribe to that paywalled site.

Its established that a low percentage of people are convinced into signing up by a paywall. There for, posting paywalled articles to a news aggregator detracts from the experience of everyone who chooses not to subscribe to that particular site because it robs us of front page real estate that could be held by other non paywalled but interesting stories.

Consider a news aggregator where every link went to a paywalled site, so many disparate sites that you couldn't afford to subscribe to all of them. Would you find the aggregator more or less valuable than one that had freely available information.