- Vanilla NPC fleets very much do obey the 30 ship limit outside of rare bugs (I've seen second-hand cases where a fleet apparently got "doubled"), and if they didn't they'd be easier to deal with, as without the 30 ship compression much of the fleet would be fodder frigates and destroyers rather than actual threats.
- There is no vanilla threat that cannot be beaten within the 30 ship limit other than getting jumped by multiple high level pirate raid fleets or Remnant Ordos at the same time. In particular, there's no mechanic banning half of those 30 ships from being capitals, and the player is expected to win any fair fight (approximately equal DP) except on rare screwups.