When you block a user, you should clear the chat on both the users, not only about who locks
Concrete example (everyday)
I send pictures to a guy (private pictures, nudes, whatever) then i realize later That this guy is a liar or one of Numerous pic collectors (profile pic of just asking for your ...)
This is a crucial point, it Undermines interaction With People has now Shall you always know That you contact anybody even liars and pervert can keep all the pictures you have sent.