If you were to construct a graph of all the features implemented by one browser and then copied by the others, after a while it would look like a chain link fence.
As correct as you are you'd be surprised how many features we use where implemented in Opera first. Surprisingly large amount, which they then threw away...
I give the Opera guys a lot of credit (I met a few engineers years ago at a conference and they seem like awesome dudes too), but one can hardly blame them for "throwing it away."