[jazzyjackson]

Because if it's just a screenshot or your own copy/paste, I have no reason to believe it's real. The only hint of authenticity is that it's served from twitter.com. The fact that there's no way to prove a tweet even happened after it was deleted or account banned seems like a problem to me.

[jeromegv]

Exactly. A screenshot can be altered. The original embed with twitter javascript was proof that this existed.