An analogy: when someone writes a song and then they need to name it, they will frequently choose a word or phrase that appears in the lyrics. When Leonard Cohen sings “hallelujah” in the song of the same name, is that a “title drop”? I assume not.
What does the article purport them to be? Right at the top I see:
> A title drop is when a character in a movie says the title of the movie they're in.
That makes no distinction if the title or the script came first. The article does call out movies who do that in a cringe or obvious way (like Suicide Squad, which had prior art) but also includes movies where that is unavoidable, such as Barbie.
More importantly, it doesn’t matter which came first. As soon as you make a line and a title the same, the line becomes a title drop. The audience sees the final product, not the process.
> An analogy
That analogy doesn’t work. Songs are typically repetitive and a few minutes long. Everyone expects them to name the title. A movie, on the other hand, is an experience that asks suspension of disbelief from you, it tries to engross you in its world over the course of multiple hours. When a character title drops, in a second you’re suddenly and forcefully pulled back from the illusion and reminded you’re watching a movie.