As engineers we have poor soft skills that lead to weak professional networks
Yeah, I dunno. I mean, some have poor soft skills, definitely. But I would argue that engineers in many companies are simply insulated more than other groups. The biggest reason for this is that Engineering is thought of as a cost center, which has a number of resulting consequences.
Other groups like Product are exposed to many other groups (Sales, BD, Exec, Engineering) and so naturally their networks are larger and more diverse.
So it looks a bit weird to them and the thought process is something like "this guy is talented, what is wrong with him that he's a walk on? I'm not willing to find out, pass."