Reason for the default value of mobile blooming intensity

I found it in the source code and the editor that if one doesn’t use post process volume in his/her project, default post processing will be implemented at runtime in mobile rendering pass.
With this default post processing, multiple effects such as vignette and bloom will be there with default values. And the intensity of blooming effect is 0.675 by defualt.

According to the final image, I can’t see any, or at least no obvious blooming effect, But all the post processing expenses are still there. What is the purpose of this default setting? Is there any reason for the specific 0.675 blooming intensity?