New York apartment brokers are a frivolous class of overpaid, lazy parasites who collect 12-17 percent of a year's rent for doing virtually nothing. They also handle the nasty work of ethnic screening (which is, yes, still present in the real estate industry), if you've ever heard of a "code 22" building.
Brokers for engineers (and bankers, traders) exist on the business model you described. They're called headhunters. They won't work for equity.
Headhunters generally don't work for equity you're correct. That doesn't mean that there isn't some market for it though.
The real downside on that is that (as someone who has been one) headhunters have a hard enough time as-is getting their fee occasionally from clients. If working WITH headhunters seems to be a pain in the ass, try being one and keeping the client and prospect in-line with a model that you can actually get paid on is rather difficult.
Brokers for engineers (and bankers, traders) exist on the business model you described. They're called headhunters. They won't work for equity.