I had the same question as you months ago. I use to only do arrangement view but now love session view. I fill up the cells with different variations beats and melodies. I then start “clip launching” to experiment and eventually discover something unexpected. I record my session view then I fine tune it (or add) in arrangement view.
It’s more fun with a controller like the APC40, APC20, Launchpad or Push.
They go hand in hand really well for production. Session is the building blocks for ideas and arrangement is where you finalize your track, levels, etc… Session is certainly also for performance.
I personally like playing clips i have created while recoding into arrangement but there are times i just drag and drop clips into arrangement until i get sections i like. I don’t know if you can create an entire song from start to finish just in session however.