thanks for posting this insight, I would add that there are positive feedback loops from some parts of your behavior and would also counter the brother's conclusion that "sending an additional message
never works"
in these kinds of threads, everyone is already primed to the worst case toxic scenario, or some other uncollaborative toxic scenario, specifically from the idea of the lowest denominator man harassing women
the reality is never so rigid
many dating profiles advertise their instagram, many times that is just a vanity project to gain followers, many times sending a message on Instagram or some other way to get noticed on Instagram can lead to agreed upon in person interaction such as dates and hookups, many times sending a message is fruitless because that person gets so much attention and their inbox is not useful, or because that person just hasn't checked their messages yet
I have absolutely had one night stands with someone I saw on a dating app, never attempted to match with, messaged them on Instagram and told them I saw them on the dating app, and went out the same day.
I've done that with women that I never even mentioned that I saw them on a dating app first. Beautiful people. The proverbial "thirst traps".
Sometimes we never even follow each other on the social media site. Just all DMs.
I've had flings and relationships with people that only reply sporadically. Or who give one word responses but are completely talkative in person. Or who apologize about not responding often because they are actually busy people who aren't trying to send a hint at all.
and the most important part of this? I have dozens of these low effort threads out there. For every one where its supposed to be interpreted as "a woman changing her behavior to be offstandish because they can't tell which man is a creep" there is "a woman thats not trying to send a hint at all collaboratively communicating like everyone else, good thing you tried again"
I would wager that most people do not keep track of whether they sent one girl 4+ unreplied messages in a row over any time period and its freaking her out, versus the conversation that will be replied to eventually. I try to be cognizant of "how it looks" no different than trying to be cognizant of how walking past a playground on the walking trail on the way to the grocery store looks. But changing my behavior because people can't tell which guys are going to go full stalker mode and assault people? Unlikely.