It seems that committees, corporations, clubs and countries can and do exercise agency. That a committee has done A is not a claim that all or most of the people on the committee have done A (in fact, one person might have been deputed), and some of the things that a committee can do seem to be things that no individual can do (e.g., collectively deliberate). Thus, there seems to be good reason to introduce the notion of collective agency.
Now, some people go one step further and say that the collective agency is exercised by an entity—the committee, corporation, club or country—that is an agent. Here is an argument for this further step. For x to exercise agency, x must think (deliberate, etc.) But if x thinks, then x is. (Otherwise the inference "I think therefore I am" is invalid.) Therefore anything that exercises agency must be. And to be is to be an entity, a something or other, (a tode ti, to use the terminology of Metaphysics Z).
So the move for positing an agent where there is collective agency is not unjustified. But the move has the following consequence: committees, clubs and countries are persons. For it seems to be a conceptual truth that only persons are agents. To be an agent, one must be a rational being, after all.
But if committees, corporations, clubs and countries are persons, then to dissolve a committee, corporation, club or country is to kill a person. Therefore, to dissolve a committee, corporation, club or country requires reasons that have the kind of gravity that killing a person requires. But that is absurd, at least in the case of committees, corporations and clubs. While it is wrong to kill a person because her work is more efficiently done by someone else, it is not wrong to dissolve a committee because its deliberations can be more efficiently subsumed under another head. And while it can be permissible for a state to dissolve a corporation or club that refuses to accept members of some minority group, this kind of discrimination does not rise to the level of a capital crime—we would not, for instance, think it acceptable to execute a sole proprietor who exhibited racism in hiring.
Therefore, it is absurd to say that committees, corporations and clubs are entities that exercise agency. And if the argument from collective agency to collectives being agents is sound, then it follows that committees, corporations and clubs do not exercise agency, except in an analogical sense.
Notice something, though. My argument above is carefully phrased to apply to committees, corporations and clubs. It might be argued not to apply to countries. For there is some plausibility to the idea that a country can only be permissibly dissolved for the gravest of reasons, reasons akin to those that justify execution (think of the partition of Germany after WWII as a form of capital punishment on the country). Still, I think this is mistaken. Reasons for two nationalities within a country to separate need not be as grave as the reasons for killing a person, if the separation can be done in a peaceful way (perhaps the separation of the Czechs and the Slovaks is an example?)
It could also be that there are some genuine collective entities. Thus, it could be that the Church is a genuine collective entity. Certainly the Christian is likely to say that to try to destroy the Church is worse than trying to kill a person (but, fortunately, destroying the Church is impossible). It could also be that a Christian marriage is a genuine collective entity, and that therefore to try to break up such a marriage is akin to attempted murder (again, fortunately, only death can actually break up a Christian marriage).
But even if there are such supernatural collective entities, it is clear that the phenomenon that gets analyzed by some as "collective agency" is not limited to them. Thus, if the argument from collective agency to collectives being agents is sound, one needs a different story about colelctive agency.