To clarify, the fact that WhatsApp wasn’t free (but very cheap) was a positive in my mind as well. I didn’t intend “not free” in my comment above to be derisory.

Also, to add some nuance: WhatsApp wasn’t free (ie it was a subscription based app) mainly in US / Western Europe IIRC; but was in fact free, as in no subscription charges, in some lower-income country app stores, eg India.