I am somewhat baffled as to why the "PUA" discussion has had a strong negative connotation. As you say, there's a ton of benefits for everyone involved

There's at least two groups of people who potentially stand to lose from widespread discussion of PUA: women, who may fear that they will be duped into choosing low quality mates by males emulating the behaviours they use to identify high quality mates and men who are already successful with women who may fear increased competition.

These sources of antipathy to PUA are rarely consciously expressed but given how crucial mate selection has been to reproductive success throughout evolutionary history you might expect strong negative reactions from those who sense a threat to their interests. Much of the strong reaction to PUA seems to me to stem from this.