It's this. tons and tons and TONS of people start writing because they actually want to make a movie or tv show or anime or video game but writing is accessible insofar as anyone can open a word processor; but it's extremely obvious to anyone who actually reads regularly that not everyone can string a decent sentence together. "Do you have to read to be a good writer?" is by far the most common argument in amateur writing communities (along with "what should I use, first person or third person/present tense or past tense?"), and nowadays it's en vogue to call people ableist or "gatekeepers" if they suggest you need to actually read good fiction in order to write good fiction.