I see no reason why you [i]can't[/i] show up with a tank or fighter-jet.
-Aside from the possibility of being sidelined for a mission or two.

Dedicated starfighters, however, are not particularily viable; since capital-ships and assualt-transports would usually fullfill those tactical needs. While other mechs would be quite capable of also performing boarding-operations at the same time.

But you are welcome to try.
-That is to say they likely do exist and perform their duties quite well, but usually perform a very limited role.

tl;dr: [u]It'd be like room-clearing with a [nuclear] bazooka,[/u] [i]probably not a good idea but I'd love to see it happen.[/i]