As I work at a cloud provider I have a different perspective on the mix-ins. The problem is that at scale there is no one customer type. Some customers absolutely require a specific way of configuring things, while other customers require exactly the opposite. Cloud providers are always trying to add more features to please all people, its a fundamental side effect of growth. And an often unstated aspect is that the most custom features are often extremely high value ones that were added for customers that worth large amounts of money to the business, even though the other 90% of small users and startups may not need that.

I think mix-ins can be a way to make the growth in features accessible while not overwhelming. Out of the box mix-ins can provide 80% of the value for 80% of the people and the long tail of 20% customers with the super custom needs that are worth high dollar amounts can still build their own custom mix-ins that target their specific use cases.