Right you are talking out your backside there on the Sony front, speaking as a Z1 Compact owner, with a sister with a Z3 Compact and her husband with a Z5 Compact.
Basically Sony have been doing waterproof with a 3.5mm jack "something" for decades, and the phones are no different. Everything *before* the Z5 had a cover for the microUSB and a magnetic charging connector.
The Z5 ditched the magnetic charging connector (which is a shame) and introduced a fully waterproof microUSB connector that does not need a cover.
Then after being first to the market with waterproof, they ditched it as everyone else started doing it. Way to go Sony not.