this^If that is not an obligation, neither is self healing. Or, roles by classes are totally optional. Fighters should use wands with UMD instead of melee or ranged attacks, Rangers should spec in healing, arcane casters should go melee everytime, since nobody can expect them to use their class given spell repertoire.
Your view of totally optional utility does not compute.
The expectations of divine casters healing the group come by inherently given spells. You expect a melee class go into melee or at least use weapons which are appropriate.
If you do not want to be that party member since you got an authority complex and see your personal freedom of choice *dictatored* then just stay out of groups who might expect you resembling that archtype of healer. Where is the problem with that?
The whole argument between those 2 camps is just absurd. Play with ppl. you can get along, else, don't meddle with the others. And at least give advice to those, who are searching for it.