Distribution, Analytics, Multiplayer, Anticheat, Publishing Services, Anti Piracy, Storefront, Sales, Mods, Custom Content Integrations, Localisation, and most importantly discovery (things you pay for dearly outside on mobile).
They never had need to convince developers that the fee is worth it and they never had to retroactively change terms of service. They have continually invested into the system and built the trust.
Most of all, Valve chose the long term sustainable business model when everyone else in the industry tried to extract per download charges from gamers. So gamers chose the company that sold them their game collection, just in the cloud instead of nickel and diming.
And developers chose valve because they were infinitely more trustworthy and offered better tools than any of the legacy publishers. They never increased the fees because they made bad bets either (and they had a few like VR)
Yes there’s a case to be made that the 30% should be reduced now, but realistically few could compare Valve to Unity when it comes to execution and long term value balancing for developers and gamers.
