I don't object to parry on its own but I would object to baking in parry mechanics that are explicitly designed to get around having a cleric.
I am curious as to what you mean by "get around having a cleric".
In my ideal game, the specific composition of the party should not matter most of the time.
For example, if a party composed of a fighter, a rogue, a monk and a wizard and another party composed of a fighter, a rogue, a cleric and a wizard were to undertake the same generic adventure and fight the same generic encounters, they each ought to have to rest at approximately the same time. The presence of the cleric should only matter occasionally (say, less than 10% of the time): in the case of asymmetric hit point depletion mentioned by DonAdam, and in the case of encounters with undead.
With the exception of these circumstances, if the cleric-less party can fight four encounters before it has to rest, the party with a cleric should also only be able to fight four encounters before it has to rest.
In my ideal game, there is thus no need to "get around having a cleric" because whether or not you have a cleric, the party has approximtely the same level of capability. For me, it is actually a problem (or at the very least, a weakness) if a party with a cleric would, on average, be able to take on an additional encounter before it needs to rest.