Again, being polite is engrained into women practically from birth, which is why I do sometimes respond. I’ve actually made some great friends from unsolicited messages, but never when that message assumes a romantic interest without even inquiring if we’re on the same page. It’s the real-life equivalent of women being nice to men who interpret all kindness as interest rather than good manners. Clarifying interest is just an important part of consent for men and women, regardless of where the interaction begins.
I didn’t frame it as leading with “are you interested” because I don’t think that has to be the first question. I do think that hitting on someone via DMs is problematic, but having a conversation with someone you’re interested in, in the hopes that they may return the interest, is understandable. It should just be clarified before proceeding further.