Appstore Policy: Why do apps stop using appstore and instead install from web sites? Today I've seen this message from SourceTree app (gui repo-manager):
'You have a behind version that supported now. We move from appstore and you need to download application from link below.'

Why did they abandon the appstore?

I think that appstore is a great app-manager, but why was this app removed?
From SourceTree's Blog:

Mac App Store Note
A final note just to say that we no longer publish to the Mac App Store due to sandboxing restrictions. Check Steve’s blog post about sandboxing for more information.