Let's review the basics, of what we already know, to clarify a few points about assists.
Logic says you pass the ball if a teammate has a better chance than you to make a basket. Best example would be where you steal the ball, a teammate runs down court ahead of the pack and you send an outlet pass to him. He gets two points, you get an assist. If you shoot from where you passed the ball, your coach will pull you. If you don't see your open teammate and dribble the ball down court, your coach will pull you.
On a 2 on 1 fastbreak, if you have the ball and you're covered, you pass it. Assist.
Now, take the set offense assist. PG has ball at top of key. C sets a screen. SG runs around screen and gets open. PG passes to SG and he makes an open shot. PG gets the assist but you could argue it belongs to the C, he got the SG open. The SG could ask for an assist as well, he got himself open.
Hockey gives multiple assists, why not the NBA?
SG passes the ball to PF who has posted up. PF makes a few faking moves, dribbles around his guy with a fake or two more, and scores. No assist here. The PF created his shot.
If it hasn't been mentioned, when a playoff series begins with a dominant point guard, the other team studies how that PG gets his assists and adjusts their defense. Passing lanes, rotations, matchups; everything is different than regular season. A team that relies on their PG to get them looks will get frustrated if the passes to them have been thwarted or there is a defender in their face whether they have the ball or not. That could cost them games, and as recent history has shown, it has. Ask Nash, Kidd, Paul, Williams, etc...