Complex sentence: Drawn and Quarterly was at the forefront of the maturation comic books saw in the 1990s, publishing and promoting the works of adult-oriented Canadian and international artists, while avoiding genres like superheroes, which publisher Chris Oliveros saw as stifling comics' growth.
Split into simpler sentences: Drawn and Quarterly was at the forefront of the maturation comic books saw in the 1990s, publishing and promoting the works of adult-oriented Canadian and international artists. The publisher avoided genres like superheroes, which publisher Chris Oliveros saw as stifling comics' growth.