Using Alexa for tasks like this is a qualitatively different experience. Hands-free/voice control can be very useful in that your hands can be busy, and you don't need to find or walk to and manipulate a device or remote.
If you're cooking, the timer on your oven should literally be right in front of your face.
Every use case I hear parroted to justify the installation of audio surveillance devices in our homes sounds like a solution desperately in search of a problem. What do you plan to do with the milliseconds of time you may have saved?
Sure, but I can ask Alexa what the weather is like while actively doing something else, like say before brushing my teeth or while in the shower. Or while in my kids closet, picking out clothes for the next day.
And while I can set a single timer on my microwave/oven, or set them on my phone, being able to set a timer, hands free, while cooking is pretty damn convenient. I can set a timer while my hands are dirty from mixing meat for meatloaf or handling chicken.
There's something to be said about the convenience factor, and that's what most technological innovations are about, making life easier or more convenient.