It's a case of different expectations. You expect an "intelligent machine" to get it right and you're exasperated when it gets it wrong.
It's kind of like saying that using a rotary phone UI on your smartphone would have been okay, because we've managed with it just fine for a long time back when we had rotary phones.
Even in a limited form its still something new that we've never had before. For people that lived alone there was simply no other option but to be nearby to hear the beep. The whole point of Alexa is to have something that can take over some of the things another human would normally have helped you with.
It's kind of like saying that using a rotary phone UI on your smartphone would have been okay, because we've managed with it just fine for a long time back when we had rotary phones.