I do find that people use the word 'dedicated to a job' to be a positive thing. But actually for a lot of people who are 'dedicated', they use work as a filler for for an emptiness/gap in their lives, dedicated to never being alone/bored etc rather than dedicated to the outcomes and their patients/clients.
I am always wary of working with people who get so invested in their jobs at the expense of any other personal development, because eventually it causes them to lose perspective. And as a manager I actively discourage people always working overtime or taking on the hard cases because they are too invested and wrapped up in it to do it justice. For my husband in the police, they will pull people up when they find they're getting obsessed with cases and not maintaining distance - because it's not healthy for the victims and the officers.They can even be strongly encouraged to take leave. It seems like the supervisor were trying to do the same with LL according to the messages shared - you need a break from ITU, to get away, shut off etc. So it was only a matter of time before she started failing at the job, irrespective of whether she is guilty of murder or not.