Opinions can be decisions

Stacker follows the Ford model: you can have any colour you like as long as it's black.

Good design is what you leave out. Choosing what to leave out means understanding exactly functionality is needed and why.

A cloud platform is only ever built for a software product, and changes to software source code needs to be carefully managed.

Open source tools for managing source code are standard solutions, so there are lots of third party services which implement them.

You are of course, free to simply install them yourself and use them, which takes time and understanding.

Stacker installs and configures an open source tool then integrates it with a software development life cycle that includes software packaging and distribution within your platform.

By giving up flexibility, you gain a working integration with less service providers.