Specialists have their own list of things to do to get masteries. Instead of people playing objective, you have people trying to smash others with shields non stop or hunt down sentries to disable and such. It takes away from natural game play by setting goals that don't really line up with the objective, or having tasks that don't help with capping the objective.
The ones I've looked at tend to be performed using each specialist's trait. Falck has to heal and revive. Mckay has to get kills from a height advantage. Dozer is a close-quarters tank. Boris has to get kills with the sentry gun. Rao has to hack enemy vehicles.
I think all of them can be used to play the objective. The problem, then, is that players don't PTFO, but that's not exactly new - it's always been that way.
