Vladimir it'll be a lot of headache without any real benefit from Upwork's POV. Making the connects transferable will open up many "business" opportunities, say, nurturing hundreds of accounts until they collect connects more than what's paid (I believe there are still ways to gather free connects) and sell it for $0.10 each.
Yes there are countermeasures, but again the effort-benefit wouldn't match. Even online currencies in games are rarely transferable now? There were times where people in online games run simple tricks like windows automated task(?) to do something in online games to collect 'online money' and sell them cheaper.
