How do you know who you can message with it if the app can’t check who has it?
You ask them via other means? It might be slightly inconvenient, yes, but you almost make it sound like even SMS is an impossible task; SMS is not even that old and none of the millions who used it before there were even apps to do so had much of the problems you mention. Also because not everyone has a usecase requiring to know who has what app.
I run WhatsApp on an Android instance with an account solely for that, so no contacts etc, and literally all my contacts/groups in WhatsApp are people who at one point told 'let's do this via whatsapp'. Then again, I don't need to message people I don't know with it so I don't have any problems.
Do you, every time you want to message someone, manually copy in their number? For every person you communicate with?
No, just once, or else they send me a message and we're talking.
tldr; ok I'm not 'most people' in this regard, but still I think you're making things look way harder then they actually are
SMS is 25+ years old -- I only know I had it on my first phone -- and the absolute ubiquity of replacements (of which WhatsApp is just one) suggests those problems are real ones for a lot of people. If you're not "most people" in this conversation, that's a pretty big caveat when talking about how the problems are not actually so, really.
You ask them via other means? It might be slightly inconvenient, yes, but you almost make it sound like even SMS is an impossible task; SMS is not even that old and none of the millions who used it before there were even apps to do so had much of the problems you mention. Also because not everyone has a usecase requiring to know who has what app.
I run WhatsApp on an Android instance with an account solely for that, so no contacts etc, and literally all my contacts/groups in WhatsApp are people who at one point told 'let's do this via whatsapp'. Then again, I don't need to message people I don't know with it so I don't have any problems.
Do you, every time you want to message someone, manually copy in their number? For every person you communicate with?
No, just once, or else they send me a message and we're talking.
tldr; ok I'm not 'most people' in this regard, but still I think you're making things look way harder then they actually are