Why atheism always has a burden of proof

[Vincenzo Vinny G.]

Scientist A: "Blargoxium is the newest element, I have discovered it"
Scientist B: "I will now find evidence to deny this".

^^ When does this ever happen in reality? Rather, its

Scientist A: "Blargoxium is the newest element, I have discovered it"
Scientist B: "Interesting. What information do you have to support your claim?"

Actually, the discussion is more like this:

Scientist A: "I have discovered the newest element Blargoxium!"
Scientist B: "You have provided insufficient proof of your discovery! I do not believe Blargoxium exists!"
Scientist A: "What is sufficient proof?"
Scientist B: "No idea! Whatever proof you bring, is insufficient!"