I'm sure passengers had sufficient force to overwhelm then but were caught off guard by groups with practiced plans. Had both groups been armed the same thing would have happened since one knew what was coming and the other was just going about its ordinary business.
Apparently YOU forget that the pretense that this was an ordinary hijacking not a suicide mission and that stopped them from acting. After the 4th plane had word from the outside that these were suicide missions the passengers prevented that one from being used.
All of which proves my point, not yours. Sorry.