WhatsApp has video calls. WhatsApp also has a significant user base amount illiterate people. They've built a clever intuitive system where you hold a button down to record a voice message. Obviously it shouldn't be recording without the user asking for it, but there's a reason for it to be an option.
Edit: I realized you might be referring to WhatsApp not having much ad data. True, but their parent company Meta does.
Edit: I realized you might be referring to WhatsApp not having much ad data. True, but their parent company Meta does.