this is just objectively untrue - if it were true then trans women participating in sport wouldn't be the big issue it is currently, especially in the US with executive orders at a federal level, individual states passing legislation etc..
Ditto to dating apps wanting to cater to, for example, lesbians - they have issues with trans women wanting access.
Pretty much any area where females wish to meet among themselves will have trans women either demanding access or trying to shut it down - whether it is an app or a rape counseling session or helpline or a shelter etc..
If grouping by gender identity is valid then why not also by sex - sex-based rights are important to some people and grouping with people of the same sex is something some people wish to do in various circumstances.
A biological woman attending, for example, a rape support group might not feel very comfortable around males in general. That some man present has chosen to identify as a woman shouldn't negate that such a group may choose to be organised on the basis of sex rather than chosen gender identity.
Simplistic slogans like "trans women are women" are taken as absolute by some activists and the notion of biological sex being important still is completely dismissed or waved away with some dubious "sex is on a spectrum too, look intrasex people exist" type argument. This results in ridiculous stances like the image posted previously re: sucking a "woman's penis" being straight etc... The super straight idea satirises this stuff perfectly and was instantly recognised by groups campaigning for sex-based rights - in particular, including LGB people, some of whom quite readily added in super lesbian, super gay etc... That in itself isn't transphobic, it's a completely legitimate response to the absolutist position that "trans women are women" and therefore the exact same rules that are applied to biological women must be applied to trans women without exception.