Was it due to the mechanics of the machine itself or something else?
Probably a combo of stupidity and being locked on a linear plane.
I read that bench to the base of the neck worked the upper pecs, as I was all broscience at the time. At the bottom of rep 8 with two plates, my ac joint suffered a 1st/2nd degree separation.
Being broke at the time since I had just graduated, I was told I had a pec tear by a chiropractor who lifted at my gym, who generously sold me calcium supplements to correct it. I didn't lift for 6 months, then went to a doc and got clear, and spent 50 bucks on the weight gain supplement with the word 900 in it, and started my path to perma bulking and getting very strong and having a gut.