Thing is, you can also construct a list of All-Star level PFs who haven't won anything, eg:
Stoudemire (In his prime rather than now)
So it's not the case that having an All-Star calibre PF is enough to lead you to glory either.
On the other hand, there are several very talented PGs who have won championships recently:
Kidd (admittedly, this one is asterisk worthy given that he was a bit older at the time).
The point is, for both positions you can construct lists of very good players at that position who have both won and not won championships. If you're only considering one of those two lists, then you can't really draw accurate conclusions about whether such players are necessary.
Parker in '07 wasn't considered elite. He was still building his way up there. I would put him on the borderline of the elite PGs at that time.
Billups was not elite, borderline like Parker. Iverson/Arenas ruled the PG position back then.
Rondo was nowhere near elite when he won a ring.
Kidd deservedly has an asterisk.
And those PFs you mentioned, only a few were what I would consider elite would be Amare, pre-knee injury. The rest are just good all-stars. There's a difference between these guys and Duncan/Dirk/KG just like there's a difference between Joe Johnson and Kobe/Wade.
All I'm saying is that having an elite PG is not as big of a deal as having an elite C/PF/SF. So if it came down to having Dwight or CP3, I'd take Dwight every day of the year(assuming he's healthy). Because a superstar C is more valuable than a superstar PG.