fewer steps, actually. as a user, you reach into your backpack pull out the battery pack, and put it on phone, check that it's charging, and then move on with your life. Replaceable battery, there's the extra steps of powering it off, opening up the case, taking out the old battery, putting in the new battery, closing the case, powering it on, waiting for it to boot up. So many extra steps!

You could reasonably add a howswap battery with a few minutes of charge if the screen is off, so rebooting isn't an issue.

Granted old button phones booted so fast it wasnt that different from starting. So doing that was overkill.