He had trouble with Nate because he threw every punch to knock him out, used techniques that weren't going to land (wheel kicks) with full force, and then he kept his hands down and gave Nate no respect. Not to mention Nate has some of the best boxing in MMA, and is tough as nails. There's a lot more to it than that, but it wasn't his lack of a lead jab hurting him.
Go back and watch some of McGregor's earlier fights and you'll see it's different. His movement, his change of tempo to break rhythm, his change in levels (his body shots probably won him the fight against Mendes for example).
I think he let the fight against Aldo go to his head, he got overconfident, and he spent the entire time against Nate pretty much trying to knock him out and loading up on everything. McGregor displayed some very complete striking leading up to this point, though, yes, and often sets up his left hand with a probing right hand as a jab or a hook.