It's roughly the same idea as the continuation rule on fouls. The intention of the rule was to recognize when a shot was occuring or in the process of occuring.
When they try to apply hard rules to it, everything falls apart. Like the unwritten rule that if you didn't dribble again after contact, it was a continuation foul even if you didn't decide to shoot until after the contact and/or blatantly traveled after the whistle. They finally had to rein it in this year because it had gone so far away from its original intent. For assists, this two dribble bullshyt people are mentioning makes no sense because it doesn't define the direction or timing of the dribbles or the amount of time that can elapse overall.
If a big man gets deep position under the basket and a point guard throws to him and he can drop it in, that's obviously an assisted basket. If a big man is at the high post and receives a pass and then has to juke and pumpfake and create his own shot, that's not an assist at all but they've been giving that one to Lonzo and other point guards.
Assists should really just apply to catch and shoots and passes that lead the receiver straight to the basket 
