So the Syndicate guys are kinda like real estate brokers, and AngelList is the MLS?
Sometimes a FSBO seller will offer to pay a buyer's agent 2.5% or so, unless they don't want to work with agents at all.
It's a waste of money IMHO, but some people like to have an agent involved. I've had far better luck selling property on my own than using agents though.
Any real estate agent in the UK offering that would get laughed out if town - 2% is common, 1% is realistically negotiatable