I kind of agree, but given the amount of locking[1] that would entail, the drop-off in performance would have those self-same users squalling about how slow it

I kind of agree, but given the amount of locking[1] that would entail, the drop-off in performance would have those self-same users squalling about how slow it was . And then they had rewrite everything with a (NOLOCK) without understanding the implications are even worse ("hey guys, I put this hint everywhere and things run really fast now!"). I know this because I've seen it. IIRC Jim Gray said that Repeatable Read is 99% of Serialisable anyway, all serialisable does is hide phantoms. [1] speaking for MS SQL, which is mainly locking based.