Why Auto-cancel redundant builds option excludes the default branch?

What is the reason for excluding the default branch after the implementation of Auto-cancel redundant builds option?

Hi there! By design, the “ Auto-cancel redundant builds ” functionality does not apply to your project’s default branch. However, here is a workaround that will allow you to enable this functionality on any branch:

It’s been well covered that it’s by design, the question is why that design choice was made. We’d like to understand this because its not clear, and it’s frustrating to have to use this hacky workaround to do something so simple.