You're absolutely right about the 90s/70s revival. Punk, Stoner, Grunge and others genres from that era were very popular. It seems to have faded out a bit, but there are A LOT of 70s style rock bands in my country still.

And as you said bands like Sleep, The Melvins and others used the heavy Black Sabbath sound combined with a punk/grudge attitude and brought fourth a whole new genre in the 90s.

PS. Nice work!