In my mind, scalability is the best problem a startup could ever have.
It means people demand your product so much that you need to concentrate on making more and more of your product. Definitely better than too little demand.
It means people demand your product so much that you need to concentrate on making more and more of your product. Definitely better than too little demand.
Now imagine a graph data structure (any site with a news-feed/following functionality). You can get 10x increase in edges without a 10x increase vertices.
Some kind of products also increase in usefulness (and demand) as they increase in user growth, so solving scalability problems is necessary to their success. It isn't, however, sufficient.