I don’t think it’s fair to generalize that feminists don’t shave their armpits. I am sure some, and maybe even many feminists don’t shave, but there are plenty of other women who also simply choose to not shave. Mintel, a consumer global market intelligence research firm with 13 offices in several different countries recently reported that “there has been a steady decline in millennial women removing hair from their legs and underarms”.
Perhaps the leading reason is that shaving foam and hair removal products can be bad for the skin and many women, again not just feminists, prefer more natural beauty products.