I don't think many people that use the term understand the premise of a walled garden. Especially the ones that use it in a derogatory fashion. When a walled garden has a door, is it any less of a walled garden? Have you ever been to a walled garden without a door or some other entranceway? Does anyone think that a walled garden would be better without a wall?

Sorry for the random thoughts.
Which has nothing to do with what is referred to as a walled garden.
Only if you don't consider web apps to be apps. Which is completely reasonable.

Google would probably disagree.
Apple has a nice walled garden AND a public garden in the same device.