My DD uses the blender on her Bosch food processor to make smoothies using all sorts of ingredients and it blends extremely well (yes, she does use kale
and fresh beetroot and spinach!). What the blender won't do, of course, is pulverise nuts, which a NB will do. But the processor itself does pulverise them - in fact she uses it to make nut butters and tahini etc. So I guess, if she wanted to have a smoothie that included nuts, then she could process them first and then add them.
I'm not going to claim that making smoothies this way is as good as using a NB, because I haven't tried one.