"As they were coming out, they found a man of Cyrene named Simon, whom they pressed into service to bear His cross" (Matthew 27:32).
Why was Simon made to perform this task? Because Jesus stumbled as He carried the cross, right? That's what so many people believe. But if you look at the gospel accounts, there is no mention whatsoever of Jesus stumbling while on the way to be crucified.
There could have been many reasons why Simon was pressed into service. Maybe Jesus was walking slower than the soldiers wanted, so they got someone else to carry the cross. Perhaps Simon looked at one of the soldiers the wrong way and they forced him to do this. It might be possible that Jesus stumbled. But in reality, we don't know. Any reason we might give would be purely speculation.
But many people choose to believe that Simon was called to bear the cross because Jesus stumbled. The thought of Jesus stumbling and falling underneath the weight of the cross can have a great emotional impact on someone. It could even bring them to tears. Preachers could use this emotionalism to their advantage in trying to provoke one to respond to his message. So this idea has been popular through the years.
Our goal, however, is not to make people cry. Our goal is to bring them to the point of faith. Faith is to be based upon the word of God (Romans 10:17), not our speculations and imaginations.
The point in all of this is to remember to "examine everything carefully" (1 Thessalonians 5:21) and test all teachings with the Scriptures (Acts 17:11). We must not believe something because we've always heard it, it sounds good, or it makes us feel good. We must believe what God has revealed in His word.