You named the two biggest platforms [0], YouTube and WhatsApp are the social media.

This is kinda like asking if Saudi Arabia and Russia are petrostates lol.

[0] https://en.wikipedia.org/wiki/List_of_most_popular_social_pl...

They were made into social media, but when they were aquired they were just video hosting and sms replacements with little (no?) social engagement aspect.

Yes, few of the prime examples?