anyway, thought?
I think there are several problems with this idea, even ignoring cases where your opponent has no creatures to trigger Oath. Here are a few off the top of my head.
1. You can't Oath up Vault or Key when you're holding the other piece (or have Oath+DT instead of Tinker+DT).
2. Oath is slow. If you're staring down a lethal swing, Tinker->Sphinx quite possibly saves you. Oath does not. If you're on the offensive, you're giving the opponent an extra turn to find answers or just blow you out.
3. The bot is typically considered the weakest of Oath's available fatties. It does not affect board state immediately, as does Iona or Don. It is slower (and generally more vulnerable to hate) than Emrakul. This exacerbates problem 2 above.
4. Oath is vulnerable to much of the same hate that is ridiculously ubiquitous. So long as Vault and Shops continue to be a presence, that hate is unlikely to disappear.
Edit: I hadn't been on the boards for a couple days, and didn't realize how much the other Oath thread blew up. Lots of people who are more qualified than I am talk about this stuff in more detail over there. I guess this still works as a short and sweet listing though.