Anyone interested in a somewhat scary era for comics might be interested in Steve Bissette's recounting of the great "mature audience label" controversy from 1986-ish. Basically, comics like Watchmen, Dark Knight and Miracleman were tickling the edges of the "comics are for kids!" boundary, and when the tumult made the mainstream media ("Comics Are Dirty!!"), a few retailers and comic companies pushed for labels. Which could have made certain books off-limits to some major retailers, essentially removing them from the marketplace.
Real people like my pal Marv Wolfman lost their jobs when they protested corporate decision-making, and retailers were hurt and/or lost their businesses when police busted their stores for selling what would now be PG material to minors. So it was not an insignificant moment. The series is running in chapter-chunks on Steve's blog at: