The sender might want to tip for a specific note but still make it anonymous. Tip on profile level is different the receiver wont have a clue for which content. Also a variant could be to reveal you zapped the note but not disclose the amount of sats on nostr.
Discussion
Hmm, 2 good points. Then a question can come up, do you want to be able to disclose later your zaps, or if you zap anonymously, it will stay anonymous forever.