What makes a product 'better' is more than just the qualities intrinsic to it. A product is 'better' if it is more useful to the consumer, and in tech, more widespread apps are preferred.
For example, take Oracle. Its not that much better than most of its competition, (DB2 SQL Server, etcetera) but nearly every enterprise DB app works with it. (I know, I worked on an enterprise app at IBM, and we made it work with Oracle before DB2.) This is because Oracle has the greater market share, and the greater market share leads to a better product ecosystem, which in turn leads to better market share. In many situations, being on top is all it takes to make your product 'better' in the eyes of the customer, and to do that, marketing and sales are very helpful. (Especially with B2B)
Digg as a community isn't worth much. Digg is valuable because of the huge set of eyeballs for Ads on Digg itself and Dugg stories. It has nothing to do with community.
Digg has different value to different demographics. For the advertisers and business persons, it is valuable in proportion to the size of the community. To those within the community, it is valuable inversly proportional to the size of the community - unless you're in part of the community that likes videos of small children hitting grown men in the genitals with baseball bats.
The problem isn't that the community is valueless - it's that it is very difficult to monetize other people's contributions.
Better sales/PR does not make what is being sold better. It is business development, not product development.