Because she is carried. Her haki usage is basically non existent. And let's not act like good haki won't overcome her DF's hax. Unless you expect the likes of Roger, WB, Mihawk, Shanks, Kaido and etc to turn into stone.
My point is, at the end of the day, Boa is a kid with a gun. If you somehow remove the gun, she ain't a threat anymore.
we have barely even seen boa fight
she is so strong that most of the fights end in seconds due to her hax devil fruit
haki overcoming her df hax right , literally only a handful of people can do that
and 95% of them are yonko tier
who are at the peak
1 love beam to anyone without acoc and the opponent is finished
even blackbeard had to sneak around her just cause he knows how dangerous she really is
kuja haki is literally a term to determine boa's haki
i wont say she is fodder without her df
she should possess advanced armament ( barrier haki )
which is really good in terms of haki quality
not only should boa be good in cqc cause of her haki ( even in the cqc she can turn u into stone btw )
but during that entire fight if she hits u with her devil fruit beam then u are done for
i dont think any non-acoc character who doesnt have a good way to dodge her beams can beat boa
she should comfortably scale to yc2 level