but that would mean that everyone who wants to play has to get wax, probably do kyc at some exchange etc. instead of just registering with social media accounts.

To be honest I see nothing wrong in buying a few bucks worth of wax that will allow you to take part in sharing economy. I know, the UX wouldn't be that great, but fuck 'em. If the intention is purely to exploit the system, such actors shouldn't be welcomed in the first place.

Increasing the difficulty and improving the implementation would also help.

That's true but it would have some tradeoffs.