> Quota increases can be requested but the default limit tells us what AWS thinks normal usage should be for most use cases.

This is certainly not true for a lot of AWS quotas. If you hit an ec2 quota for an instance type, that isn't AWS telling you that you are using too much compute. Its there as a speedbump to make sure you have some idea that you know what you are doing and to make sure AWS can actually service your requests.

AWS will happily let you have hundreds of child accounts. In fact, if you are talking to them about your architecture they will even encourage it (assuming that it is actually appropriate for the scale of your organization).

I think this just tells us author is using a method counterintuitive to what AWS would recommend, so while you may try it out that it probably isn't best practice and so when you screw up then you will just be left pointing to some blog as to why you chose the direction you did.