Isn't that what the Type 10 - Defender is meant to be?
It is actually, but since the release on it was "Thargoid Focused", had a small (class 6) Power Distributor and the fact that neither Frontier or the Elite's Description says it's a part of the "Big 3", people have just seen it as a failure on all fronts and never looked back.
Frontier then gave the ship an upgrade and put it on par with the "Big 3" but it's far too late for anyone to notice or to care.
Fun Fact: During the Black Friday period, the Type-10 was the ONLY ship to have it's Black Friday paint job 100 Frontier Points instead of 200 like the rest of the ships (including the fighters). I'm guessing it's due to it's popularity in general. How do I know? I bought it because I'm one of the few that loves the Type-10.