Several posters here are outraged over the fact that diplomats often say one thing officially and publicly, while saying quite the opposite privately, unofficially, in secret. And that in a free country nothing diplomats do should be a secret, all our cards should be on the table for everyone to see.
IOW, they are upset that diplomats are being diplomatic when it comes to dealing with foreign governments.
This thread is for those outraged persons to offer alternatives to diplomacy when it comes to foreign relations.
It's a straw man OP, with an odd circular defense of your refusal to actually quote anything you claim to be arguing against.
On the one hand this is an explicit "calling out" of these mysterious people, but on the other hand you are prohibited by the rules from calling them out, so you are limited to the straw man version instead of what they actually said.
Not being one of this mysterious group though I can clearly see your central assertion - that diplomats cannot criticize diplomatically - is absurd.
A nation certainly can criticize its associates - and should - without being vulgar, obscene, childish, or otherwise unnecessarily insulting. You can respectfully tell your brother he has an alcohol problem too without phrasing it in a way that just makes him angry and results in a fight instead of productive exchange.
It seems to me you champion lying - both lying to our own people and lying to our international associates. Stating one thing publicly and the opposite thing secretly means lying.
I don't consider that diplomacy. Stating you disagree in a tactful manner publicly while stating the same thing crudely in private is what I learned as diplomacy in my limited exposure to it in college.
In other words, you've made up your own definition of diplomacy, and it seems lying is the core tenet whereas the central definition in dictionaries or books on the subject is one of tact.
It also seems to me that the mystery people already answered your question in accordance with the standard definition of tactful negotiation - that in a free country citizens cannot very well rule when the government keeps everything secret from them, so what diplomats say should be public.
In sum, it seems to me your core premise is that lying is the definition of diplomacy instead of tact in negotiations, and that lying cannot be accomplished openly so therefore diplomacy requires secrecy.
That is begging the question.