Why it's still not possible to cut videos in GarageBand?

I understand that this program is not designed for video editing, only simple music composing. However, Apple implemented a feature to add a video and compose on top of it. This is great, but it fails in its execution for not allowing to edit at least the start and end point of the video I'm importing.

I cannot be the only person who got the idea to record himself while playing an instrument that is recorded via audio interface directly into GarageBand. Obviously, music and video will be off and I cannot sync them directly in GarageBand, because I cannot define the begin and end of the imported video.

So at the end, I need to use iMovie or any other software for video editing, making this feature of GarageBand is a big failure that is unable to get its purpose right: To make my life easier, it's not. It could've been so good to have everything in one project file. Fail, just fail!

A simple start and stop mark of the video should be a no-brainer for the devs.