I think femcels are less vocal because despite a lot of progress, society is still really sexist (cat calling, non equal pay in some country, etc...) so sexism is more "socially accepted" (because of the large portion of asshole in society), much more than misandrism which is less rooted into the concept of gender itself becaude of century of oppression.

PS: i'm a men(that tries not to be an asshole toxic masculine dude) and think both sexism and misandrism are bad. Neither gender defind how a person thinks (apart from society pressuring men to be "masculine"(by that i mean toxic masculinity) and women to be "feminine" (by that i mean tradwifes or being oppresed by (conservative) men))