T'Pol referred to early Vulcans as "an extremely violent race," with "paranoia and homicidal rage" being common. Earlier, Spock called that time "savage, even by Earth standards." While that doesn't mean that every Vulcan was a bloodthirsty murderer, it does suggest that early Vulcans probably made Klingons look tame in comparison. But the general sentiment is that Vulcan society was headed towards self-annihilation if it wasn't for Surak.
I think those Vulcans who resettled on Romulus simply found another path other than logic, or else they would have destroyed themselves too. Perhaps by developing a fascist society, the Romulans used fear to maintain order (fear of the authorities, fear of speaking out against the government and being imprisoned, fear of your friend betraying you, fear of some stranger accusing you of not being a loyal Romulan, etc.). That kind of creates a strict society where hardly anyone makes a move that might be remotely viewed as being out of line, perhaps.