The fact that you felt the need to compare the points you made with knowing the composition of water just demonstrates the need for citations. If these points about psychology were actually as commonly known as the composition of water then you wouldn't need an analogy- you would just sarcastically remark "A citation? Really?".

Maybe if psychology was required in high school and earlier the way chemistry is we would all know this already. As it stands, at least 3-4 of us didn't realize that these points are widely known and non-controversial (and have taken the time to say so) so I think there is good reason to think that these points aren't known by non-psychologists the way certain chemical compositions are by non-chemists.