100% true - Though I wouldn't say necessarily a placebo, it does have some stuff in it that thickens the actual shaft of the hair, but in no way does it block or inhibit DHT on the scalp. It won't 'fix' the problem, it'll just make your hair superficially appear a little thicker. Period.
Nizoral 2% - It's truly the only shampoo with any factual backing to having an impact on DHT.
the only shampoo that is shown to be somewhat benefical for male pattern baldness (in proper scientific studies) is ketocanazole. It comes in 1% otc and 2% prescribed. It has to be used three times a week, left for ten minutes before washing off.
The 2% can leave your hair feeling dry.