This is one of many examples where both sides of this discussion are correct.
TT hasn't displayed the tools that are generally considered critical to be a truly successful QB in the league and win games "by himself" on a consistent basis. That's not to say it can't be successful - see P. Manning -2015-16, T. Dilfer, etc... but it's a rarity.
On the flip side, what do the Bills do as an alternative? There doesn't seem to be much in the draft, there is definitely nothing out there that's better, and you certainly can't trade for a guy because why would a team trade a franchise QB.
So it's a tough situation, we just have to hope TT grows into top tier QB, develops his skill reading defenses, throwing between the numbers, and throwing on time and guys open. In the meantime, keep acquiring QBs a la Cardale Jones in hopes that one shows promise and can become the guy.