Playing devil's advocate I guess but I think blanket statements that "X is definitively offensive" is kind of harmful. In my own experience both my wife and female friends have been offended or disgusted by catcalling, but they've also been legitimately flattered by polite compliments.
The notion that suddenly a woman doesn't like to be told they're pretty just isn't 100% true for all women, and the OP seems to be suggesting just that.
I have told women they were pretty before with zero intention of harassing or bothering them any further. One of my longest running female friendships started simply because I walked up to her and told her I thought she was very pretty, complimented her style, and then told her to have a good day. She ended up tracking me down and we became friends. It made her feel good, not harassed.
Is that different than more aggressive "catcalling"? Sure, but my point is that the OP was pretty aggressive in stating that its offensive to tell a woman they are attractive, period. That it reinforces the notion that looks are all that matters. I'm just saying that isn't 100% the case, and sometimes a person likes to be told they are attractive, if compliment seems sincere and isn't aggressively delivered.
Context is important, every person and situation is different. Depending on who you ask, what I've done and compliments my wife have gotten could be considered a form of catcalling and offensive to some, but they are flattering to others.
The key is to just be respectful people.