Phytoestrogens absolutely bind to estrogen receptors and do affect the body. While not as potent, it still mimics estrogen.
The comparison here is like saying psilocin doesn't bind to serotonin receptors because it isn't serotonin.
Since any other reference probably wouldn't work here, have one from one of those holistic medicine places: https://denverholisticmedicine.com/blog/2018/5/17/phytoestrogens-friend-or-foe
You shouldn't need to spread misinformation to promote a hobby.