The cut off the top is the biggest reason. See fortnight as an example - this is an excellent case to look at to understand incentives of skirting around Google and Apple's stores, even if inconvenient to end users. If a user wants the software (eg if the demand is significant enough) the inconvenience to the user may not be a factor. For the rest of us... The App store as a platform is too powerful to ignore. https://www.theverge.com/2018/8/3/17645982/epic-games-fortni...