It all starts when a nerd extends their sense of self to encompass their favourite operating system, programming language, open source license, or anything else they have may have developed a certain strong digital addiction to. Because the nerd's sense of self is involved, advocacy is, in fact, a particularly retarded form of shameless self-promotion.
Once their ego is firmly attached to their chosen fetish XYZ, an advocate lies in wait until the subject of XYZ comes up on an unrelated or distantly related Internets forum, newsgroup, or mailing list. Only at such a point will they begin to actively advocate XYZ. Beginning with what they consider to be eminently rational arguments for why XYZ is teh g00dz, they progress through various stages of persuasion: benchmarks, anecdotes, opining, rhetoric, sophistry, ad hominems, whining, and finally quitting XYZ forever.
History does not record a single person changing their mind due to exposure to advocacy on any subject whatsoever.