For me this would create more clutter and require more of my attention to ensure the devices work the way I want them to and that I have them on hand. Yes my MP3 player doesn't show notifications but its another device I need to keep with me and keep charged. Buying a device for the sake of it unless I have a real need just feels like consumerism.
I was skeptical until I kidnapped my wife's kindle and started reading on that instead of my phone. I recently added an mp3 player too and there really is something about the intentionality of a dedicated device that make it more enjoyable and more focused than using my phone for everything.
But to your point, there is definitely a lot of performative/consumerism basis - if you visit the Emulator subreddit for example there's an increasingly common joke that nobody ever uses their device, just buys the new one to collect it/post it online for internet points.