There is no set criteria for MVP voting. Nobody dictates to the voters what stats they have to consider or ignore.
Your point is nonsense anyway. Voters can and do look at a variety of stats, and TDs in a season can be a function of just throwing the ball a lot, so it has to be looked at in the context of the overall stats to judge how much value to give it. QBR is part of what got Romo strong consideration for MVP in 2014. Remember, QBR is actually takes into account a lot of other stats, such as INTs and completion %. That's why, despite being 2nd in the NFL in TD's, Winston was not considered an MVP candidate, or even a top QB for that matter. The fact that he threw 30 INTs and only had a 60% completion percentage killed his QBR and killed any chance at being perceived as a top QB.
Besides that, MVP is not only a stat driven award. Especially at QB, almost everyone considers things like leadership and inspiration and other intangibles to be a big factor, plus team success is always considered. Assuming the gap isn't huge, a player with somewhat better stats on an 8-8 team is much less likely to get MVP votes than a player with somewhat lower stats on a 13-3 team.