Its bankrupt because those fighters existed and so must have been based somewhere, it not difficult to make a connection to some support ship-class we never seen being their base, this is speculation true but the connection can be made.
A new support ship class is not at all required to explain the presence of fighters, though. Any ship with a reasonably sized shuttlebay could hold a few, and the Galaxy-class' main shuttlebay was so big that it could easily hold several. All this assuming you remove the shuttles first, which could be done at a starbase.
Of course by that logic every large ship should have a single hangar. But this is a situation where gameplay takes precedence over Trek accuracy. Dedicated ships makes more sense from a gameplay standpoint.