A backpack's built-in laptop compartment is designed around one thing: keeping the laptop away from the rest of the bag's contents during a drop. It does that well, but it does nothing once the laptop is out of the bag - on a desk, in a locker, or handed to airport security.
A standalone sleeve covers that gap. It travels with the laptop even when the laptop isn't in the backpack, and a good one adds a second layer of corner protection that most backpack compartments skip entirely.
The two aren't competing - they're complementary. A sleeve inside a padded compartment is genuine belt-and-suspenders protection, and it's the setup we'd actually recommend for anyone traveling with hardware they can't easily replace.
