How would Visa/Master know? Steam doesn't include information about which games are purchased in the receipt (at least as far as I know). Unless they have some sort of back-channel they wouldn't know what's being charged back.

If Valve was getting a complaint from Visa/Master about charge back rates of certain games, I believe they'd be more forthcoming with that information. What we're seeing here is more consistent with Visa/Master taking offense with what the platform offers.

In either case, I find the lack of communication from Visa/Master deafening. If Visa/Master was seeing high chargeback rates from incest games on steam. Why would they not eagerly offer that data?