No transwoman I know, or have ever known, believes that women should lose their identity.
According to Ray Blanchard's typology, there are two types of transwomen. As follows.
HSTS (homosexual transsexuals), and AGP (autogynephiles).
They are completely different.
Homosexual transsexuals are usually effeminate gay men, with either internalised homophobia, or have suffered from homophobic abuse. They feel more comfortable presenting as female, rather than address all the issues.
AGP individuals become aroused at the thought of being a woman, often in faux humiliating or degrading circumstances. Often late to transition, they are frequently married and fathers, and may have been cross dressing for years. They are heterosexual.
Neither of these two types promote feminism and they are both rooted in sexism. But at least the former don't fetishise women and their oppression for sexual kicks.
It's also the former who are not generally transactivists. And this might very well be the transwomen with which you are acquainted.
Unfortunately it would appear that they are in a very small minority, at the moment.
What was a practical issue for them, has now become ideological and highly politicised.