- it's free (or inexpensive compared to international SMS)
- it doesn't require any technical expertise whatsoever
- it's cross platform
- it already has traction
I can't think of any alternative which has this combination of properties..
It has come to the point that my wife and I barely use SMS anymore and are actually saving some play money on SMS thanks to that thing.
And that is bad news for carriers worldwide yes, but not that anyone really feels pity for them anyway.
This situation resembles the early period of the Internet, when users of Compuserve couldn't send e-mails to users of AOL (and other way around). It sounds completely weird today, but how is this situation with IM networks different?
Understandably there are historic isolated networks (AOL, MSN etc.) which predate any serious federation efforts, and even they are slowly enabling XMPP in some ways. But creating new closed ones in the present time is just weird and only serves to make the situation worse.
For example, if I'm going to go on a date with someone and we've swapped numbers that's enough for us to talk by SMS/iMessage/WhatsApp, whilst we probably[1] don't know each other well enough yet to expose our digital lives to each other on Facebook.
[1] - This entirely depends on things like age, social norms, how much personal information is on your Facebook page etc. Also, depending on are you going on a date with someone you already know vs. someone new. Mostly the point being that anything that just needs a phone number has a low barrier to communication while also not leaking any personal information (other than your phone number).
I know it was used as a precursor to iMessage type eaperince to send 'texts' and images using only data, so was perfect for communicating across countries with no carrier charges.
Phone numbers are logins. Everybody with a phone already has one, so they don't have to do the whole 'create/verify an ID/password' dance.
If you have friends in other countries, this avoids roaming SMS charges. And if you are from Ireland, or Greece, lots of your friends are in other countries.
Yes, that's exactly the catch. Why should you require them to install anoter app if they might already use some other IM network? Approach of WhatsApp may be simplifies the initial registration step, but it adds to the global mess of the non interoperable IM networks. Negative impact way outweighs any potential comfort benefits, and authors who promote such things are to be blamed for it.
> Everybody with a phone already has one, so they don't have to do the whole 'create/verify an ID/password' dance
Actually you might want to do it, since numbers change, while IDs don't. Plus you want to authenticate the other party if for example you need a secure conversation (such as with OTR).
One time configuration / registration is not really a burden. All users are familial with that process. And they don't do it each time they read their e-mail for example. As I said, the negative impact of non interoperability proliferation is way more significant.