Does anyone have any theory as to who is responsible for these
anti-brand-name postings?


Some people are "giving type" people and like to share. (As opposed to the
selfish "me" generation people who are only capable of thinking about
themselves.)

Some people are "more intelligent" than others and teach others what they
know. For example these people might see others with financial difficulties
spending their money foolishly. And they are simply pointing out ways to
better manage money. And thus rectify the financial difficulties in
question.

As to generic vs name brand, in many cases both products are made by the
same company! They make the SAME profit by selling either! The only
difference is they tack on the cost of advertising to the name brand
product.