It's rude to interrupt people while they're talking.
Alex is in a team meeting where one member is presenting something when he comes up with a great idea.
Alex wants to get his idea out before he forgets.
Alex writes his idea down in his notes and waits for the presenting member to finish before sharing it.
Alex cuts off the team member who is talking to pitch the idea.
The other team member has a meaningful presentation and receives Alex's idea well.
The other team member was about to make a good point which wont have the same emphasis now.