"The White House said on Monday that recent encounters between U.S. and Chinese forces in the Taiwan Strait and South China Sea reflect a growing aggressiveness by Beijing's military that raises the risk of an error in which somebody gets hurt."
https://www.reuters.com/world/china-russia-launch-joint-air-...
That dotted line is not just a claim, it's where Chinese gunships will patrol and where Chinese bombers do exercise flights. I am actually surprised that the US government is so happy to tolerate large US companies completely undermining their own geopolitical position just to increase profits, like with Blizzard.
"The public's response, which included a boycott and a letter from United States Congress representatives to Activision Blizzard, prompted Blizzard to reduce the punishment, but not to eliminate it."
https://en.wikipedia.org/wiki/Blitzchung_controversy
I believe what all those movies and the Blizzard incident show is that the dream of large profits from China appears to be extremely successful at influencing US companies to help with China's agenda. And the US government appears to be not too successful at preventing that. Also, there is some history w.r.t. that line in movies and on merchandise:
"In pursuit of this goal, China uses any means it can to promote the visibility of the nine-dash line, displaying it on passports, maps, exported globes, movies, books, online games, clothing, tourist leaflets, booklets, television shows, and more. A case in point—in October 2019, a nine-dash map was visible in “Abominable,” an animated family movie jointly produced by China-based Pearl Studio and America’s DreamWorks Animation. In 2018, a group of Chinese tourists wearing T-shirts with a nine-dash line drawing arrived in Vietnam."
https://amti.csis.org/science-journals-a-new-frontline-in-th...
That means in my opinion, this is mostly the CCP showing off their political clout. "Look we can make them include our line!"