I feel a semicolon is more appropriate; I would not declare misuse.
Prescriptive grammar brings the drama; that’s why I love it. The second clause is more a continuation than an explanation.
This works, though. There is one reason I love prescriptive grammar: it brings the drama.
It's the "that's" that's the issue.
Prescriptive grammar brings the drama; no matter what I do, I can't stop loving it.
> There is one reason I love prescriptive grammar: it brings the drama.
Masterclass.