But Bob's question was not about asking what the consensus opinion was of those "millions of people", it was a question about what was your individual personal opinion. Or more specifically, what dissimilarities you had already seen when comparing the two bodies of work that prompted your admonition to him to perform a similar comparison, with the unspoken expectation that he would see the same.
It is a basic premise of classical logic that one cannot successfully assert the falseness of an argument without being able to point to the truthful condition which gives rise to that falsehood. In order to successfully argue that Bob's argument is wrong, you must be able to back that position up by telling us what you believe is right. Simply offering the opinion of millions of others does not necessarily meet that metric.
OK, I personally think that the work of HCB is in a different league to Vivian Maires in terms of composition, decisive moment, Zen photography, contemplation of space and vision, realisation of differential focus, perspective, lighting, geometry, framing, contemplation and respect of subject. But then this is only my opinion.