Governor is just filthy when Chapel is on the board. Buy one, Chapel everything else away, and you can give yourself a gold every turn - and once you start greening you can use your Governor to draw three more cards to your hand if you can't make $8. Or, if you've got too many gold in your hand, well just remodel some into Provinces. And that pesky Chapel that always sits around after your done using it...well it can be remodeled if there is a useful $4 on the board.
Sure it helps your opponent, but given the pace at which this can finish off a board silvers are just not going to help them very much. I haven't played anyone who played optimally with these two cards, so I can't say for sure what the bonuses would do if well-executed. But the couple times I've done this, I've gotten 5 or 6 Provinces within 12 or 13 turns and closed out the game. In solo games I've been able to pretty reliably get all 8 Provinces within 16 turns by buying one Chapel and two Governors.