It's no secret. People ban the Vasari rebels because of the mobile starbases.
The funny thing? The race with the best counter to the mobile starbase is.....you guessed it. The Vasari. Specifically I'm getting a phase missiles and their ability to focus fire a target.
I'm not 100% sure, but to make things even more amusing, I think the VR get the unique phase missile upgrade that increases missile damage even more.
Yup, tech is Advanced NME Warheads, and increases the damage bonus to 30%. Then there's the ability of bombers to hit the SB from behind (bypassing Frontal Shields).
I'm wondering if there's any answer to a VR fleet with a Kultorask, mid-large sentinel count, and a ton of bomber-carriers - light frigates would get frozen & torn apart by the Kulto (and cruisers would soon follow), bombers get erased by Charged Missiles on the sentinels, and any capitals/titans/SBs get focused down by 100+ bomber squads. Guess a titan+capitals with Jam weapons might be able to pierce it, but that kind of plays into the OPs point.