As one of the biggest social media sites, the move toward better representation for LGBTQ+ users is not much of a surprise.
Other social media platforms have previously added pronoun support in varying degrees of complexity. Facebook has supported pronoun choice since 2014, but it was limited to he/him, she/her and they/them. Other apps like Lyft and OkCupid also allow users to present their pronouns.
Users, even those who don't belong to the LGBTQ+ community, have openly displayed pronouns over many sites. Trans advocates and allies have promoted wide pronoun use as a means to normalize it in the wider public.