Think of it from your male companion’s perspective. To him, the beckoning men are at the very least, innocent rivals for your platonic attention, and at the very most, combatants lusting to injure or defile you. He has three choices: confront them, shield or mitigate it from you, or do nothing and leave it up to you.
If the beckoner appears to be dangerous or a romantic encroacher and your companion does nothing, your companion would appear to the stereotypical woman, as well as feel to himself, pathetic as a friend or as a man. Within him, he must intervene unless he trusts your instincts implicitly toward this situation with whom he sees as a fellow male. To him, verbally confronting a simple cat-caller could be safe depending on their attitude and physical build. Distraction by changing the topic of conversation may also work. In either case, however, a hostile or unpredictable one may throw a punch or pull a weapon on him, especially since your companion would be positioned as a rival to his goal. Considering that outcome, he is left with shielding or strategizing with you to ignore verbal advances as the option that from his experience has the least potential for physical harm (the path of least resistance to not escalate the situation). That is probably why he conferences with you. Like you, he doesn’t want to agitate the unknown, particularly in case you become a liability rather than a dependable comrade. Other men may jump head first into confrontation with the belief that doing so will end it as quickly as possible. Yes, he does not understand your methods or calmness because he is experiencing the situation from a male’s perspective, being unfamiliar with it but nonetheless facing another male who is a potential threat to his stereotypically weaker companion, you. There is a mountain of instinctual stereotypes and anecdotal evidence that form the basis for that inside both of you. Men may not get cat-called as frequently, but they do get picked on by aggressors, and from that is where they likely imprint their survival strategies for these types of situations. If you want your male companion to understand, grab his arm, look him in the eyes, and tell him firmly, “I got this.” If you take the lead and assure him to trust you, he will have your back. Later, explain your methods to him and to other men as you have done, not passively on a blog directed at fellow women. That is, unless the aim isn’t to vent or fish for empathy but to mobilize them to communicate with, not to, the men in their lives about their own experiences and ways of resolving it.
In cases where you are alone, similar impressions apply. However, the concerned onlookers also do not know whether you know the apparent cat-caller or what your intentions are. Most anyone, I think, who shows concern and is not in a hurry to be somewhere would linger until they judge the danger level to you and themselves at which time they will intervene or leave. The presence of watchful eyes, I have to disagree, is a deterrent if the actors are aware of them and presently able to feel social shame. See authoritarian regimes. Culture, of course, is the larger concept housing what is socially acceptable. Compare it to rampant accosting of white women by men in India, rape of women and children by men in South Africa, or apathy of others’ general hardships by mainland Chinese.
Humoring a caller as you do is an effective way to deal with some of them, but if gone on too far, it could understandably be seen by your companion as careless exacerbation, appeasement, submission, or even welcoming. Again, by reciprocating, you are making it uncertain to your companion whether you know the person or what your intentions are. Discuss it with them before accusing them of victim-blaming. Upon reflection, another way I can think of to dissuade an unwanted persistent caller would be to start making out with your boyfriend in front of them. You’d be sent glances, but most people would not interrupt you. Uninhibited drunks, though, are less predictable.
Harassment will happen regardless of clothing as you said, but I don’t think that after years of talk that men are partial to visual stimuli that less provocative clothing would not at least affect the frequency of harassment. It's sometimes difficult to find clothes that aren’t designed to be provocative and don’t have a low neckline or otherwise emphasize the chest or hips or are so form-fitting that they pinch throughout the day without selecting larger size or looking like a granny in a snowstorm. Frankly, I am surprised more women haven’t posed concerns to clothing producers. One would think there would be more amongst the many "practical female armor" and desexualized super hero viral posts. Men aren't left with choosing deep-V's, that's for sure.