I believe the business model is that it is near impossible to leave the ecosystem (this is also how SAP can still thrive). It takes a lot of money and expertise

I believe the business model is that it is near impossible to leave the ecosystem (this is also how SAP can still thrive). It takes a lot of money and expertise to make the migration happen. Few companies have scaling problems as pronounced as Amazon and as much of a vested interest in migrating to their own custom solutions.