They were in life-or-death situations. Usagi saying they should just give up is more than just being a crybaby, it's going to get them killed and the world destroyed. She wasn't any more of a victim than the rest of the girls in both scenes. Not including, you know, the people who actually got injured/killed. In Ami's case, they didn't have the time to sit her down and talk her out of her it. Nobody is invalidating her emotions, but you need to put your feelings aside in that kind of scenario or else you and everyone you care about will die.
By slapping they aren't putting their feelings aside. Instead they're prioritizing their own feelings at the expense of hers. It's not just as selfish as a meltdown but even worse because it's imposing one's will on another.
It was a slap. Not Fire Soul or bashing her in head with the mini computer. Usagi was the one actively tearing the team apart by trying to get everyone to quit.
First of all, even a shove can kill, and a slap can EASILY cause a concussion.
Furthermore, a physical attack is a physical attack, period. The only people who should be physically attacking heroes are the bad guys. If
you're attacking, then
you're the enemy.
Would she do that? The whole reason she's in that state to begin with is because people she cared about got hurt/killed. Someone who does that yet goes around and vaporizes them with the crystal would make for an awful main character.
Because people react differently from being hit.
Some people like Usagi are convinced by force and comply.
Other people, like myself, would start fighting back, possibly to the point of death if emotions are heightened. Anyone who puts their hands on me in a situation where it is impossible to escape has forfeited their life in my eyes, as I have no way of knowing they won't stop after the first blow, and even if they do stop after the first blow, I'm not going to be cognizant of them stopping and will continue to swing back until they are no longer a threat, and in my frame of mind, I likely would perceive their existence as a threat. So, yeah, if Sailor Mars had hit me and I had the presence of mind to fight back, I'd have probably tried to kill her, as well as Sailor Mercury when she did she same. Each would have proved she didn't care about me anyway by hitting me and might as well be the enemy.
To paraphrase the Snickers commercial, you're not you when you're angry.
She didn't believe in Usagi's strength and didn't want her getting involved anymore. Also, she just said "you'll die." If you actually look at all her actions in context it's pretty obvious that she was trying to protect Usagi in a misguided manner.
So you protect a hero by taking away their ability to access their powers?
Right. Characters can't be flawed or ever do anything wrong or else they're evil and abusive monsters.
They can do wrong....as long as it is acknowledged that their evil wasn't necessary.