I'm a competitor so I can kinda see the reasons behind her always wanting to lift more (for ego) etc. And she's not dieting right now so she will want to be progressive overloading (adding weight to build muscle), but there gets to a point where you just can't do that anymore without causing injury..sometimes it's just about training smarter rather than trying to injure yourself and sometimes going so heavy you can't even feel that muscle working properly anyway so defeats the point.
Calling people out on their form on equipment you need though, since you're a coach G, you could have showed them? No harm in simply being a nice person in the gym, everyone has to start somewhere and it's better than being sat at home sheeesssh