In the days when PartyPoker accepted American players and around the time of Moneymaker's win, playing on PartyPoker was like having a money printing press.
I agree very much with Jilly. Plus, there is another difference....the specials, bonuses, added money,
real money possible to win in
freerolls, and so on used to be a lot better in the early days online (roughly definied as after Moneymaker, and before UIGEA laws). Regardless of how relatively good/bad the PLAYERS were, the DEALS we so good that you could make money from that in spite of the play.
The first PartyPoker bonus was so much easier to clear than today. It was a SURE $200 profit from a $600 deposit.
pokerstars, you had like $120 bonus that needed only 5 points per dollar to clear, as as well you frequently had weeks they would have "double points" weeks where for the same exact play you got double every point earned.
I don't know all the current deals, but I don't think anything close to that easy to clear exist much.
And before the laws changed, there was much more competition for USA players, meaning good deals to try and outdo each other. That for sure does not exist like that anymore.