Producing and making beats are two VERY different things. I'm positive Dre produced all of Doggystyle. However, he may not have had his hands on the keyboards or drum machines. A producer oversees the production of a song, much like a director does for a movie. It's his job to get the best performance from the rapper, singers, and players. Whether or not he made the music, he still produced the album. That is why it has the classic sound. Simply put, Dre has one of the best ears for music ever. In rap, the producer often happens to be the musician & composer.
-=bumpus=-