A discussion about sync-master-info and other replication parameters

Some time ago, feedback was requested on new replication default after MySQL 5.7.  Some of the suggested default are:

• relay-log-info-repository = TABLE (previous default FILE)
• relay-log-recovery = ON (previous default OFF)
• master-info-repository = TABLE (previous default FILE)
• sync-master-info = 1,000 (previous default 10,000)
• sync-relay-log = 1,000 (previous default 10,000)

I agree on the suggestions for relay-log-info-repository and relay-log-recovery: they are needed for crash safe replication, and having crash safe replication enabled by default is a good thing.  I have doubts about master-info-repository: I do not see what benefits are introduced by this change.  I have much bigger doubts about sync-master-info and sync-relay-log: those changes bring an illusion of safety, which is bad.  Let's dive in more details about those parameters.