I'm a fan of snacking, & only have one medium or large meal a day. My digestion gets a good rest for the 16 hours I don't eat as restrctive eating times suit me, too.
Smoothies can be healthy or not depending entirely what on what goes into them. 250mls of kefir, & a handful of berries is tasty, a banana makes it more filling, but they're low on my fruit list.
I know some people who like everything ground up in a £400 blender "to release the nutrients & enzymes". I wonder if their teeth will fall out from drinking all their food. One person then binges on chips, so healthwise it's counterproductive.
Someone else I know, who cycles >40 miles a day, eats a huge cooked breakfast plus a smoothie of soya milk, banana, malt extract, & peanut butter which I'd class as very unhealthy & toxic FOR ME, but he needs a breakfast totalling my entire daily calorie intake to get to work.
What's healthy depends on a person's genes & lifestyle. Eating most things fresh, raw or cooked from scratch, with no industrial processing, or added chemicals is healthy.
If you like smoothies, eat them.