I do not think "pretty" is objectifying in the slightest. "Sexy"? Yes. But telling someone they're pretty is a benign compliment. Is it superficial? Maybe. Of course, superficiality has many facets. I would call the endless stream of weight-loss programs that are so heavily advertised as having a negative influence. I would call the magazines promoting extremely thin models and calling them "ideal" as superficial.
But telling someone that they're pretty is benign. It doesn't flatter the ego over a certain age and it certainly isn't objectifying.
I think you have a different definition of objectifying than I do. That's fine. I'm a Buddhist, so I have a very liberal definition of what it means to see something as an "object".
Phrasing and context is critical, of course. If someone tells me I'm pretty and I don't know them, it's awkward and creepy. If someone I've known for a decade tells me the same, the comment is colored by my understanding of what they mean. If someone tells me that I'm a beautiful person, that's less objectifying than telling me I'm beautiful. If someone tells me that they enjoy being around me, that's unambiguously a compliment. They're commenting on their own state of being instead of commenting on mine.
It's complicated. I probably shouldn't comment on this further since it is something I've been thinking about pretty hard for a long time and my conclusions are not necessarily intuitively obvious.
Sorry, I think I agree with this article. Pretty is just another word that objectifies people by complimenting the most superficial aspect of their being.