I'm not sure why there's a backlash to CB D this morning, haha. No one is saying it's the BEST gun ever, but it is a very good one.
It's got a very low TTK and melts at close to medium range. It's a good alternative to TLW for people that either a) don't like TLW or b) want to free up an exotic slot. In an era where sometimes TLW shots are lost to bloom RNG, Doctrine is a fine substitute that offers more consistency. It has neither the highest peaks of amazing plays of TLW nor the valleys--sometimes losing the valleys is worth losing the peaks.
It's one flaw (recoil) is largely mitigated by Counterbalance. In the same way that one can get used to taming the up-up-up recoil of TLW, you can learn to compensate for T R U C K E R L A W by holding down on the right stick until Persistence kicks in.
It's effective at longer rangers than it should be, but it's primarily a rushdown or shottie defense weapon. Once you get some practice controlling the recoil with it, you can engage at medium+ range and challenge most scouts and pulses--Ape is great at this. He uses his CB D at longer ranges than I see most able to effectively. His streams over the weekend are, like, tens of hours of examples of how Doctrine is surprisingly decent at long-ish ranges.