Yeah, this.
I think that for the kind of music you want to compose, something like Reaper or Cubase might be easier. It's probably a good idea to just try the demos of Fl, Reaper, Cubase and whatever else you can find to see which one suits your Jazz compositions best.
What does that have to do with writing music? I would say that if someone were to start writing music for the first time and immediately start using a thousand-dollar sample library, they probably wouldn't have a clue how to use the sample library and make it sound realistic.