Here most of the discussion went on Java and Php as the solution for such a system but not on asp.net. Can anyone give a detailed reason why asp.net is not preferred, although I don't know much about asp.net but I guess it is also good enough to carry such a system and I think orkut is or was in asp.net few years back I guessed from its url patterns.
most hobbyists (which is most of the people here) don't have access to the tooling needed to use asp.net, hence they tend to ignore its very existence.
The Microsoft "hatred" many religiously claim doesn't help (all the while using Windows, MS Office, and other Microsoft products...).
PHP and dot NET both are programming language applied to make dynamic Web Pages. Now a day’s both are in demand so it’s depend on your choice. To choose a language for your project is depends on your project need and requirement.