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I get it. When GoogleAmazonFacebook et al. come out with new, shiny gadgets, we jump. We're the early adopters, the people interested enough in tech to buy things and ask questions later. There's nothing wrong with that.

But I felt differently when the first smart display emerged. And then the next. And then the next one after that.

The product category has some things going for it. I like the sleek design of the Lenovo Smart Display, the privacy-first logic behind Google's camera-free Home Hub, and the smart tracking camera in Facebook's Portal and Portal Plus (minus all the privacy issues -- read my thoughts on that here). Even Amazon's Echo Show, which looked pretty janky in gen-one, has newfound appeal in its updated model 2.0.

Still, I can't figure out why anyone would buy a smart display. Allow me to present my case.

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That extra screen adds no value whatsoever

Here's the TL;DR as I see it -- your existing phone, tablet and TV can do all of the same things as a smart display -- and much better than a smart display. Since you probably already have a phone, a tablet and a TV in your house, why would you buy a smart display, too?

A bit of history, AKA I've felt this way for a long time

Back in 2014 and 2015, I reviewed two home security systems -- the Archos Smart Home Starter Pack and the Kronosight Sentri. While the two, now-discontinued products were quite different from each other, they shared one key feature: a tablet with a built-in stand as their central piece of hardware. I didn't like them much.

Here are some excerpts from my 2014 Archos review: "Archos' awkward 'tablet' hub operates like an Android tablet without any of the mobility, making the interface largely unusable and its role in the kit questionable."

I didn't stop there: "The built-in stand hump makes this tablet much more of a stationary home-automation hub than an easily-transportable mobile device. That means it has the functionality of a tablet without any of the ease-of-use."

My 2015 review of the Kronosight Sentri sounds similar: "There's a question of value with Sentri. Sure, it sort of looks like an older-gen iPad, but I can easily buy an actual older-gen iPad for less than the $299 Sentri. It would make more sense to get the iPad."

I feel roughly the same about every smart display I've come across.

Enlarge Image Tyler Lizenby/CNET

Use your phone, tablet or TV instead

The phone(s) and tablet(s) you already have at home can respond to voice commands, help guide you through recipes, show you who's at the front door -- and much more. They can literally do everything you'd ever need a smart display to do, and you already have them with you, almost all the time.

To me, that portability is key. Why would I want to have a video call on an Amazon Echo Show sitting stationary in my kitchen when I could use my phone for the exact same thing any time I want? And, if you want a stand to keep your phone or tablet from slipping, then buy a cheap, functional stand for your kitchen, living room -- or wherever else you think you might make use of a more hands-free display.

I'd also rather use my TV to display family photos than a smart display. It's easy to set up most modern TVs to loop photos in a slideshow, just like a computer screensaver, a digital photo album and, yes, a smart display.

The problem of time

Tech moves fast. Nowadays most of us refresh our phones every two to three years, sometimes less, like leasing a car. We use them for a bit, and then we trade them in for a newer model fairly quickly. Most of us don't plan to hold onto our phones for 10-plus years. (If you've used the same mobile phone for 10-plus years, get in touch. I want to write about you.)

But, generally, you're going to get a new phone every couple of years. That means your phone and/or tablet will almost always be better quality than your smart display. And to keep the smart display current with your phone's quality, you'd also have to refresh it every few years at least.

Since we're regularly investing in new phones and tablets, and they do the same things as any smart display (which has an awkward stand and can't go anywhere) why buy both?

Related note: With a couple of caveats, I liked the look of that Kronosight Sentri I tested back in 2015. Today it looks extremely dated.

Enlarge Image Tyler Lizenby/CNET

The gist

I've tested out smart displays enough to understand why Google's Home Hub could be a handy kitchen companion when you're preparing a recipe -- or why you might want the Amazon Echo Show in your basement to pull up a YouTube video for you while you're trying to fix a nearby leak.

But there's so much overlap in terms of what smart displays can do compared to the phones and tablets already in your life, that I can't make sense of them as a growing product category. They aren't as smart or as high-quality as most of our mobile devices, they aren't portable, and they aren't cheap enough to make those rare cases of utility worthwhile.

I can do everything I need to do with the phone, tablet and TV I already have, often with a better result. I have enough screens in my life. I don't need a smart display, too.