I worked at FB, and I think they would probably do OK if they entered the space as they are very smart about physical infrastructure, but the most plausible explanation I heard from an executive (forget which one) when asked this was that they are already building out at a very fast clip, and feel that they can make a better ROI by using that infrastructure themselves rather than renting it out.
If the growth knobs were turned off across all it's products and spare capacity became a thing, then it might make sense, but at the rate they are building there is no purpose to being a middle man.
Make a code optimization and save 1-2% of CPU on the web tier and you will be a hero.
Right now facebook has a couple options when a new network emerges. Buy the competitor, clone the competitor, ignore them, compete with a not completely similar product. Why not another option, like "take a percentage of their profit in exchange for service." I dont think it should be looked at as just as direct ROI, but also as a hedge against future obsolescence. Its a better position to be in, to be the ocean, if everybody wakes up one day and jumps ship.
Visa and Microsoft make a ton of money being a grease or tax on other business, a small shaving of money in exchange for massive efficiency, instead of trying to BE every business. Is anyone offering an out of the box Social Graph as a Service kit?
It would also be a huge growth opportunity for Facebook Ad Services, to be THE ad marketplace of all new social networks. And in a play right out of Adobe's playbook, buying some things like bigcommerce, ecommdash, shiptstation would position them to sell underlying services that allow their customers to compete directly with amazon, ebay, adobe, salesforce. There is surely a lot more money they could make selling saas and pass, vs becoming another generic iaas provider.
