They never did, only when their profits are in danger do they care and the big payment processing companies, that's literally every credit card company, PayPal, and anything else like them, HATE adult content of any kind being associated with them by the fact that players use their payment processing services to buy said content on Steam, which is why, for example, DLSite cannot allow PayPal for direct purchase of content, but can allow PayPal purchase of their store currency, so the payment processing service companies threaten Valve behind closed doors to pull out if Valve doesn't do something. Valve wants to keep up the facade that they care about the players and creators using their service, so they strike a middle ground and say it has to be taken out and patched back in from off Steam. This is the whole reason AI Shoujo has a patch on the Illusion website like Koikatsu does.