Back in the days when App Stores hadn't launched Android and iOS did not exist, apps for platforms like Palm, Pocket PC, Symbian, Blackberry etc worked like how Windows software still works today - you bought them directly from the developer's website. Stores like Handdango and Pocketgear were multi platform app stores who were taking 30% cut. I remember even back then there were voices being raised against those fees. But back then, those were not the only ways one could distribute their apps. None of the smartphone platforms back then mandated developers to distribute their apps only through their store. Even when Android launched, it was open and these stores carried Android apps as well. Apple launched the app store and changed everything in the name of security and user experience. It was just a shameless money grab by a giant corporation.
Microsoft got all the flack just for bundling a browser for free with OS while Google and Apple have been arm twisting developers into paying 30% of their revenue for years.