The sad thing about phones being he primary (and in many case the only) computing devices for most people is that they lose the possibility of separating the tasks that the do on the phone vs the tasks that they do on a computer.
Now in the past, it was because the "desktop version" was more featureful/powerful due to the constrained resources of the mobile platform. This still holds true; even though mobile computing resources aren't constrained, the UI and display can be, somewhat.
But also the mobile app may exhibit some features unavailable on "desktop"! Because of the nature of the sensors and secure platform, you can have sophisticated features available on your smartphone that aren't possible to replicate on any other platform. Nearly every built-in Google app is like this and if you read the documentation, you can easily see the differences.
And of course there's the mobile-only apps that malfunction or refuse to install on Chromebook, like a ride share or something that's actually designed to be used "out and about" in meatspace.
So there are many times when I am lying in bed, for example, phone in hand, and I attempt some task and realize that the features I want are only available on "desktop" version, and then I got to make a mental note to address that when I'm on "desktop". Or vice versa, I'm puttering away on the Chromebook and it balks at something I'll need to use my phone for. Or the worst-case scenario is when I need to have 2-3 devices all directly at hand to do some dumb thing like printing out a page! AUGH!
Most people really do not need the dedicated device, whether it's a laptop or desktop, to use the Internet they way they want to.
I have had every type of computing device, including pre-smart phone PDA's, and ultimately when I need to do something that isn't mediated by an "app", I will always gravitate towards doing it on an actual computer.
Now - while I do prefer a laptop as my primary machine - it is essentially a desktop, as I typically use it 90% of the time attached to either a dock at home or the office, with external screens, keyboard and mouse.
(Heck - my latest machine only gets about 75m of battery life... it is more a luggable than a "work-at-the-beach" kind of machine (i9, lots of ram, etc.) - and I am perfectly happy with that arrangement)
Any limitations on smartphones are either ergonomic or entirely artificial.
In fact, it kind of runs the other way: even my "portable" "real" computer is terrible as, say, a camera, or level. It's a bad GPS navigation device, both due to the form factor and it's entirely lacking the hardware for it (technically they can have this, but very few do).
There are lots of things my phone can do that even my laptop, let alone my desktop, practically can't.
Assigning tasks to devices can be done due to the capabilities of each device but also due to other factors, like what behaviour you want to influence. For example, if you want to spend less time doom-scrolling/on social media/whatever, moving these tasks outside of the computer you have in your pocket and into the computer you need to sit in front of helps.
Wanted to add here they are also fixable. Most phones can be used with a keyboard, monitor and mouse. Reading from a phone or tablet on a beach beats doing so on a laptop! Most of all people continue to create improved tools for voice recognition.