Comment by jvalencia
This takes time and effort, thus, lost opportunity cost. The thing that makes these providers worth it, is that it lets the business focus on their core competencies and just add-on as they scale without worrying about complexity. A business owner who hyper-optimizes for every contract is unlikely to be focusing on growing their business, even if their business is more efficient on paper.
It would make me very uneasy to have my company be 100% dependent on another company. It sure is easy and convenient to just go to AWS/Azure/GCP pick all the components I want and plug them together but I'd say leading a company is not always choosing the easiest but sometimes the most sensible option.