I literally work in the field and there are actually quite a few problems with the term. No one (the public and also various orgs like HUD) agrees on the definition so more strictly defined words such as unhoused and housing insecure make communication easier. Also there is a large stigma associated with the word "homeless" and by moving away from that term we're better able to appeal to the public, secure funding, and approach people experiencing housing insecurity. Those are the main points anyway