There's certainly nothing wrong with doing your compositing outside of Blender. I used to do it when I first started using Blender since I was more familiar elsewhere. But I would argue there's benefit to compositing in Blender. The simple virtue of not having to save out image files was enough for me to give Blender's compositor a go. Then I got hooked on the convenience and capability.
It seems like a big commitment to do it in blender since it gets baked into each frame
Understand that you can easily render passes out of Blender and use those in the Compositor for max flexibility (like you would use Nuke or After Effect, or DR). Again, I used to do this in the beginning: always breaking my scenes into render layers and passes. But over time I realized I rarely made any changes to the passes in post. So now I use the compositor as a basic treatment step rather than a significant modification process (as I demonstrate in this course). It is a commitment like you say, but not a terribly consequential one unless it's taking many hours or days to render a sequence. In those cases I will utilize passes and a "proper" composition.
Does that make sense?