Thanks for correction. I treat NDAs as enforceable, I stick by my word. Just to be clear: I am entirely against IP theft (taking actual source code from a company).
Nonetheless the idea of "social network for X" is not unique and deserves no protection similar to what a chip architecture or a machine learning algorithm may receive. Not that there aren't ambiguous examples e.g., using SVMs to categorize users of a social network or using an emulated RISC architecture to profile the GUI front-end of a web application (such as a social network) but in the cases the idea is not very useful without the engineering chops to put it into use.
True for employee noncompetes with no other relevant factors; not true for NDAs.