Alexa - when it works - can do things that cannot be done better in a different ways. There are times when turning on a light or unlocking a door with a phone is better than the alternatives as well. However there are a lot of times where the 100+ year old way of doing the task is better.

Even if voice assistants worked perfectly every time they would still be worse than the switch by the door for controlling the light as you enter/leave. However if you are in bed it may be that despite the current annoyances Alexa is better for controlling the same light.