[Tommy Angelo]

"In a high stakes game where the players are able to remember things like who raised before the flop, etc etc, is having the initiative, ie, putting in the last bet in the previous round, a fundamental advantage?"

Yes. It's a relentless advantage, like being last.

How many times do both players have nothing?

Of those times, how often does the pot go to the bettor?

Of those times, how often is the bettor who wins the pot the same person as the bettor who bet or raised on the prior round?

The answer to all three questions in the games I play in is: most of the time. Anything that wins pots most of the time when everyone has nothing is huge.

And there's other things too, that initiative buys. Getting checked to, getting reads, and becoming last to act.

"Imagine a Tommy Angelo-style player who does a lot of calling even with very big hands. Not having the initiative makes little difference in his ability to bluff at various points and take it down immediately."

I bluff plenty, and lots of my bluffs work, when I have the initiative, and because I have the initiative.