As opposed to a device picked in no small part (excuse the pun) because it's small enough to fit in my small hands. It has a speaker the size of my fingernail and a microphone that's even smaller again.
I use my phone when I can't use my laptop or workstation. It's a compromise device, and while I love and heavily use my phone, it's not a replacement.
Everything on my PC is better than on my phone. The screen, the input devices, the audio input, the audio output.
Plus a decent web client is always going to be more portable and will let you catch people on whatever device they want to use. You can get it on Windows phones and tablets, Linux devices, PCs, Macs and consoles.
A web-based version may also enable me to hack in a convenient workflow. Heck, I'd be tempted to hook it up so I could use it while stuck in traffic. And maybe if I get addicted to the platform even add a Twilio number so I can use it if I'm stuck without mobile data somewhere. Not a proper substitute for an API, but good enough in the beginning.
