As you suggest bringing this to your local trade body and making a formal complaint is probably the way to go. It will take a long time and a lot of complaints to get there though. In the mean time avoid them, both the buy and sell side.
You can derive that is very likely the case based on the intelligence and composure of the rest of their post. You can also derive it directly from the full paragraph text, which is not referring specifically to Upwork, rather it is referring to Silicon Valley broadly, and why "things" developed the way they did with how SV firms have tended to treat customers/users.