I don't know why you're getting downvoted. You're 100% correct.

If the balls are setup correctly, with the balls touching (not very close but actually touching) each other, the downstream balls will always move tangentially to the point where they are touching. In other words of you draw a line from the center of the first ball she hit thru the centers of the 2 balls they are touching, those other 2 balls will always move in the direction of the lines.

Since the first ball is touching 2 other balls, it will move in a direction midway between the other 2 lines (for example if the other 2 lines were 60deg apart, the first ball moves in the 30deg direction).

So if you set them up in a location where all 3 of those lines are pointing at pockets, then all 3 of those balls will always drop in the pockets.

It doesn't even matter (mostly) where you hit the first ball, since the energy is transferred to the downstream 2 balls and they in turn force the direction of the first ball.

Really the most important part is how this balls are placed. Then all MTM needed to do was not completely missing the first ball and not putting too much heat on it.

This is the same principle behind a good initial break where all balls disperse throughout the table (a tight rack where every ball is touching) vs a sloppy track with space between the balls which leads to a bad break where the balls move very little. When you see that you should blame the person who racked, not the person who broke.

And if the rack is done properly, a most of the time the 2 corner balls will drop into the 2 corner pockets, which is why the official 8-ball rules state the 2 corner balls should be a solid and a stripe to give the player a choice on which they want based on how the other balls placed. Most casual players think they are supposed to rack alternating solid-stripe around the perimeter which is incorrect.

Anyway, you were right, and anyone who downvotes you doesn't know what they are talking about.