It can be done with whatever: - record video (notebook / smartphone / ...) - send / share / embed into some other software (messenger / wiki / ...)
You are obviously good at marketing stuff (to people who don't know better) and monetizing stuff that is basically free.
That cries for an award with a title like "silver ferengi medal" ;-)
They work so well because the barrier is extremely low: it's literally a single interaction, keep the "button" pressed and the message is sent automatically upon releasing it.
And yet nobody was using voice messages when you had to: - Tap "attach" - Tap "audio" - Tap "record" - Tap "confirm" Or, worse, use a separate app and "share" to WhatsApp.
UX is important. I assume this service is based on a similar principle.
"Please don't post shallow dismissals, especially of other people's work. A good critical comment teaches us something."