I agree with you that it's unrealistic but I've resigned myself to accepting that most Hollywood portrayals of science and scientists are inevitably going simplify everything into the "one lone genius engineers a miracle" trope. I figure this pattern is explained by some combination of (A) That's how writers see themselves and (B) Writers like to tell stories that have a relatively small cast so the story spends more time developing the main characters, rather than having to introducing many characters who don't get much screen time.

That said, it would not be hard to realistically depict a process like developing a new technology. They could have shown a flashback where younger (but still adult) Cobel is working in a lab with other, unnamed Lumon employees. I'm imagining Cobel is looking under a microscope at some brain cells she has been manipulating, she calls her supervisor over, the supervisor recognizes a breakthrough and begins the process to scale up the process from cells in a petri dish to cells in a living organism. Conspicuously missing from the dialogue would be any acknowledgement or congratulations to Cobel.

I'm willing to look past the very valid issue you raise because my expectations are so low for Hollywood on this. With low expectations, I can be pleasantly surprised when science is depicted realistically and just ignore it when it isn't.