For anyone interested. I am a mod of a new small sub. When I went looking for tips and tricks on how to grow my sub. Mod help suggested crossposting and commenting your community tastefully in others.
However, as I did these things in related communities. Users got upset at what they considered spam. While some mods banned despite having no rule against promotion or crossposts. So obviously Reddit doesn’t like sub promotion all that much, and their opinion is needed ;).