Not necessarily true. The Herc is durable enough and maneuverable enough to give most adversaries a hard time in a dogfight. Responsible ordnance selection will also make your life much longer - Transcend is a good example of what responsible ordnance selection IS NOT.
The SF Dragon has nearly the same amount of effective HP as a Herc II (including shields) and is much faster and much smaller. The Manticore is also pretty close, with 500 shields and 100 hull. Same with the Mara, at 620 shields and 200 HP. And guess what. Every single one of these fighters are much faster and turn faster than the Herc II. Also, I'm fairly certain the Herc II's maneuverability is pretty close to a Medusa's, which is hardly' maneuverable enough to give most adversaries a hard time.
See, the thing in FreeSpace is, speed and maneuverability (and size, but to a somewhat lesser extent) factor much more into a ship's survivability than just pure hull. This is why bombers are inherently terrible at killing fighters in FreeSpace. For example, you could have a fighter, bomber, whatever with 2000 shields and 2000 hull, and it would be slow and have slow maneuverability. It would still get trampled on by even lone fighters, so long as the pilot has half a brain.