Is it possible to write PhD thesis (or PhD thesis level scientific articles) in Computer Science without real advisor (of course there always be formal one)? E.g. there are (almost) no books how to learn musical composition, artistic painting, cello playing - all such learning is done during private tête-à-tête studies. Maybe Computer Science is similar discipline which can not be learned by self-studying books, articles and conference proceedings. Maybe Computer Science has enough unwritten folklore that is passed only via direct contact between advisor and student? I have read many acknowledgments in thesis that ascertain this viewpoins, there are so much thanks for explaining one or another thing.
My question is about having real PhD advisor. Of course, each PhD student has its advisor by the University rules but there may be cases when having advisor is mere formality, advisor can have no knowledge and skills and the discipline pursued by the student. It can happen and it happens in countries that are not top countries.