I think the reason people are bringing up the non-clerics is because in 4E the idea of the "Divine power source" has replaced the traditional concept of "cleric". In previous iterations, "cleric" became sort of the catch-all term for any religious character type. Whether it was the full-on warrior / paladin mirror... or the more monastic type... or the god's rank and file... the "cleric" represented all of them.
But nowadays... as the OP seems to be referring to a band of divine commandos, the singular class of "cleric" not only doesn't need to fulfill all the different members of said band, but also probably shouldn't. "Cleric" is now just the term for one facet of a religious organization, and a very small facet at that. So adding in paladins, avengers, and invokers to the mix to represent all sides and methodologies (i.e. "roles") of this commando squad is probably a good idea.
Sure, you could try and juryrig the cleric class to become defenders, strikers, and controllers (in addition to leaders)... but unless that is specifically the goal of this concept, there's no reason not to use the other three classes in the cleric's place. The cleric is no longer the universal term it once was.
But nowadays... as the OP seems to be referring to a band of divine commandos, the singular class of "cleric" not only doesn't need to fulfill all the different members of said band, but also probably shouldn't. "Cleric" is now just the term for one facet of a religious organization, and a very small facet at that. So adding in paladins, avengers, and invokers to the mix to represent all sides and methodologies (i.e. "roles") of this commando squad is probably a good idea.
Sure, you could try and juryrig the cleric class to become defenders, strikers, and controllers (in addition to leaders)... but unless that is specifically the goal of this concept, there's no reason not to use the other three classes in the cleric's place. The cleric is no longer the universal term it once was.