Emphasis on medically transitioned.
Some people seem to think that lgbt activists want to make it so that any male athlete could just put on a wig, say “I’m trans now”, steal medals from women and then detransition the next day. (As depicted in that Futurama episode.)
Letting trans people who have medically transitioned for several years compete is a very different beast from letting anyone who claims to be trans compete.
For people who previously used SMS and had their contacts saved in the phone’s pre-installed contact app, WhatsApp could use all those contacts out of the box.