It's not an either/or. You can simultaneously have more trust in apps coming from the walled garden and cherry-pick with greater care the select number of potent applications that come from outside of it and are therefore harder to trust, precisely because they may be able to do more than what's allowed within the walled garden.

>Again, I'm playing devils advocate for a pro-walled-garden opinion me myself don't believe in, so don't take my opinion too seriously.

Pure cynicism on my part by default, so it's all good, mate.