You mean like if the keys were being bought off the developer's own website? G2A claims they're offering a 10x refund to the developer in such cases:
> The site said it would also start offering developers refunds worth 10 times the sum lost if they could prove keys had been sold on G2A after being bought with stolen credit card details.
The developer interviewed in the original article claims that doesn't matter because the stolen keys are being bought on Steam, not on the developer's own sites:
> Mr Rose responded saying most developers relied on sales via Steam and other third-party stores rather than their own sites, so G2A's refund offer was a "red herring".
But again, shouldn't Steam be the one dealing with the problem in that case? Why do the developers care?