This was actually inspired quite some time ago by William, but has been reinforced by others since.
Are comics for kids? I submit that this has never been true. The oldest regularly published comics were made for adults, and while storytelling has progressed since then, I think it is still obvious. I believe the trope of comics being for kids was started by the government when they decided they wanted to regulate it. The regulations have passed away some time ago, and comics have become more self-regulatory. The idea that comics arev for kids stems from the 1950s and 1960s and was false by the 1980s. In the 1980s we saw comics starting to disregard the Comics Code Authority and publish adult oriented comics without government consent. By 2000, the major comic companies started moving away from the CCA and started focusing more on adult storytelling that had far more depth than the comics of old. The change in focus was inevitable considering the shifts in comics over the years.