If Apple has top tier talent, why do they ship an OS with a huge security vulnerability? With a map framework that has memory leaks? With a messaging app that messes up the order of messages?
If Google has top tier talent, why did they create an OS that allowed a third party developer to siphon calls, contacts and messages?
If this is your argument, then no company has top talent.
"no company has top talent" is much closer to the truth than your implied assumption that even companies drenched in top talent must deliver shit products.
Well the better answer would be that top talent either work on ads or server side infrastructure. For client side its user device, battery, RAM and money and they could care less once they have thrown a free app in the face of users.
It takes some amazing engineering talent to build an app which drains your battery that slowly whilst uploading "everything" on your phone to Facebook's servers? :-)
Because swooping up all mobile audio and transmit it over would be a management decision, certainly not engineering.
This is what most likely drains the battery and your data plan.
You cannot explain this amount of drainage with CPU only.
Also swooping all kind of privacy data, like call logs, messages, contacts, calendar info is from management. Engineers really know better that this will be found out sooner and later, and then it's the end.