A 1099-DIV is sent (and must be filed) for ALL dividends received from a security --even if the dividends were re-invested and not physically received as cash. As a result of re-investing you did in fact benefit financially from the dividends. Dividend payments ARE taxed as income even if you do not actually receive a check but had the dividends reinvested in the investment; since the reinvested dividends are indeed actually benefiting you by adding to the value of the investment --in other words you did received financial benefit from the reinvested dividends, just as if you received a check and spent it.
A 1099-B is not the same as a 1099-DIV. The 1099-B relates to the price you received when you sold the security versus the price you paid when you purchased the security, and thus determines if you have a loss or gain during the time you owned the security.