> So ... you could chose not to do that for your parents. There's no way they would do it by accident.

If third party app stores were allowed, some vendors OPs parents need to use would likely only publish their apps on a different store. I would not enjoy helping my parents navigate going to the MS store for Office, the Facebook store for Instagram, the Google store for maps. The lack of fragmentation makes this much more approachable for them.

This is not a defence of the current system. That has many other problems.