I believe it's an ignorance thing. That's the only way I can explain it.

I do not understand why anyone would not want to determine before take off if everything they had was functioning the way it should. Also being a full scale and UAV pilot, I understand the importance of a full power run up as part of the pre-flight procedure. Yes, full scale does full power run up's too. In most light singles and twins full power is used for the mag and propeller cycling checks. One never, ever, takes off without knowing that all is functioning as it should be.

There's an old saying about runway behind you, blue sky above you, and fuel left in the pumps. All are useless when things get down and dirty. One might add available power to that list and not be off the mark. If you don't have the power you comitted to an activity while increasing your odds of failure.