I agree with previous posts. It is however proof that aircraft still have to be flown, even in "reduced automatics", like LVL CH or V/S. Calling yourself a pilot on the B737NG if you are only able to set a new ALT in the window, pressing VNAV, then watch the show and not see that trend vector going past the "zipper"? hmmm..
Watever button you push, you should await the result and airplane`s response. And if necessary correct it.
It shows that too many pilots nowadays try to talk to FMC`s, and let them fly the aircraft. I see it on a daily basis, with identical results. FLY first!