I noticed the same thing on the jams I took part to. If devs are worried about too much DM spamming, we could make a conservative system where user A must whitelist user B to allow incoming DMs from user B (at which time B will automatically whitelist A to reply). It would have the drawback or making message exchanges slightly slower, as B would not be able to immediately DM A, but if A is really looking for people to recruit / teams to be recruited, they’ll probably check notifications, see B’s reply “hey, I’m interested, here is my portfolio, and I’ll send you my Discord ID in DM when you whitelist me” and whitelist B.
But a good anti-spam / trust system can also do the trick. Personally I was contacted my people on Reddit exactly when they had something to tell me about one of my posts, and was never annoyed by spammers (I think? If it happened I must have reported and blocked them in a breeze, so I don’t even remember).