I think it had something to do with credit card fees
Edit: found this on reddit
Grey Markets are often done by credit card scammers which results into chargebacks by the credit institute resulting in processing fees for the producer of the game or even getting them cc banned.
Edit edit: it was Factorio - https://arstechnica.com/gaming/2020/05/g2a-confirms-stolen-game-key-sales-pays-40000-to-factorio-devs/
If it were a paid account yeah, it’d be extremely shitty. But seeing as it’s a free account, it’s their prerogative to try and get people to pay for the service. Besides, I don’t get this entitlement that spotify has to provide music for free. They’re a (admittedly greedy) middle-man that wants to get paid. If one wants free music and everything, well, time to self-host.