Yeah, I think that’s a valid criticism. Off the top of my head, the women of LotR are:

Eowyn (A good character, I think, even though her one big moment, killing the Witch King, is undercut with a pretty stupid “get it, you thought ‘man’ meant human but she’s a girl!” twist and she gets unceremoniously hitched with Faramir to tie her story off. Not Tolkien’s best work)
Galadriel (Queen of Lorien, sure, wielder of Nenya, ok cool, refuses the One Ring, well done very wise, but not much of a character in the story, more a vehicle for exposition)
Arwen (Aragorn’s objet d’amour and… end of list)
The Old Woman in the Houses of Healing in Minas Tirith (can’t remember her name, basically an old lady clown iirc)
Lobelia (Shrewish but she does resist Sharkey at the end, offscreen, so partial character credit I guess)
Rosie (Sam’s Arwen)

Those are slim pickins. I can forgive Tolkien for writing a male-dominated war story, I imagine that’s what his experience with war (and, culture generally) was like. I think his fixation on race, lineage, and hereditary right of power are more severe undercuts to his critique of abuse of power.

EDIT: 😆 I wanted to check my work and found there’s a whole separate wikipedia article on the subject https://en.wikipedia.org/wiki/Women_in_The_Lord_of_the_Rings