The current development kernel is...linux-next?

"can't we make a diff to last day linux-next and take this patch to check in a new
linux-next???"

The resulting diff would represent all the work done by all maintainers in a day.  It would be
large, and not very logical.

If I have a conflict with something in linux-next, then I want to be able to identify exactly
the smallest logical change that produces the conflict, and who did it (in case I need to ask
them about it).  It would be difficult to do that if a single change that's checked in is a
big agglomerations of unrelated stuff by lots of different developers.