In Scrum, team assigns story points to tasks during planning poker. When explaining the meaning of points, the scrum master says it is effort. So if it is time consuming task but can be done easily or it is a complex task but can be done fast they all can have the same points. So the intention is to forget about the time units and play with effort units. But in my opinion it is not fair. Why? Let me say how many concepts connected with points play as time.
After several sprints team already know how many points it can complete during one sprint. Sprint duration is fixed - say two weeks. Hence if you find your velocity say 200 points per 2 weeks then you know that the team speed is 20 points per day. Which generally means that one task which has 20 points should be done, ideally, in one day. Hence 20 points means one day. And one day, is, surprisingly, time unit not effort. If you asses by effort then you might finish it in 2 hours and you will be ahead of your sprint which is not good (wrong estimation).
Burn down charts connect points to time as well. So as in the previous case, we again can think about points as time. Otherwise, we will get ahead or behind of the sprint schedule.
Team very soon identifies with time units, probably because of 2 previous reasons.
So why we say points are based on effort and are not connected directly to time if, indeed, they are meaning time? What is a problem to say X points is Y time for team A and Z time for team B?