Jellico didn't push anyone beyond their limits. He pushed them beyond their comfort zone. As was later seen when Data explains to Geordi exactly how the captain's orders could be met
Many times during Picard's command, the crew needed to work extra hours, & achieve what seemed nearly impossible. They were willing to go that length for Picard because they trusted him from having built a relationship with him. Jellico had to demand that level of performance even though he had not yet had that opportunity. He had to just expect that it was "Starfleet's Finest Crew" & therefore they owed him that much, because they owe it to Starfleet, especially with the safety of the Federation on the line.
Riker was wrong in that he believed himself to be too important to be just a piece of the mission, instead of one of it's architects, who had a say in what should be happening. He succumb to hubris. (Not the 1st time for him, btw) He needed to be thinking his way through the difficulty & looking at it from all perspectives, instead of just becoming resistant
Excerpt From Ensigns of Command
PICARD: How are we progressing, Mister LaForge?
GEORDI: About like you'd expect. (Not at all)
PICARD: Splendid. (Do it anyway)
WESLEY: He wants the impossible.
GEORDI: That's the short definition for "captain."
Odd that he forgets that being the case, when the captain isn't Picard. They worked their asses off in that episode, & no one bitched to the point of being relieved