nazcan

Because you have to keep explicitly passing state between each callback, rather than just using the same context (which still has the ability to delete things if needed).

Bait and switch for who(m)? The companies offering services on these providers?

Their is a simple fix - get a contract and don't assume current terms will continue without it.

No incentive is too extreme - users can still switch search engines.

Do most of the authorization flows require the user to provide their password for their lock manufacturer?