(but does intend to donate to development) and doesn't hold any position of authority over the project itself.
He who pays the bills, makes the rules.
That would be true if there was some plan to have this group pay the bills, or channel all/most funding through the group (there isn't). In reality the envisioned donations from such a group don't come close to being adequate to do so. It will just be one funding source among others, not at all unlike the members of such a group donating individually.
One purpose for the group making donations, in fact, is internal to the group itself: to discourage membership by those who would seek to undermine the project. Since the group is open and anyone can join, that would be a risk. But anyone doing that will have a portion of his membership dues directed to donations to support the project, directly undermining his own interests. So think of it as a form of anti-spam/abuse.