Because WhatsApp was the first with password less-login using SMS login.
It was dead simple to use. You had a phone, installed Whatsapp, it sent you a verification text that it automatically read and verified to ensure you owned that phone number, and that was your “account”.
No user names to remember, no passwords, a completely computer illiterate person could use it, especially if their first device ever was a smartphone.
And it worked amazingly well. And there was no spam. I specifically remember sharing contacts being a pain in the ass until WhatsApp came along.
I suppose none of the others, which could have leveraged their existing userbase chose to follow suit because the companies that owned them did not have a way to make money from them. WhatsApp didn't either, but startups weren't expected to.
The initial WhatsApp plan was to charge between $1 and 2€, initially a one time fee paid after a few weeks, then a yearly subscription after one free year.
I kinda wish that had paned out.
It'd still be hundreds of millions of dollars in yearly revenue. Plus businesses.
The funny thing is that on Android, I never had to pay the fee as the free trial kept getting extended. Only my friends with iPhones paid for WhatsApp, IIRC on iOS it was upfront too!
It was dead simple to use. You had a phone, installed Whatsapp, it sent you a verification text that it automatically read and verified to ensure you owned that phone number, and that was your “account”.
No user names to remember, no passwords, a completely computer illiterate person could use it, especially if their first device ever was a smartphone.
And it worked amazingly well. And there was no spam. I specifically remember sharing contacts being a pain in the ass until WhatsApp came along.