I have mixed feelings about the need for a cellular modem. I can already easily tether to either my iPhone or iPad without paying for a separate
line.
Also as an x86 based anything, the battery life is already going to be poor and the fan is going to make noise. Using the modem is going to make it worse.
And it’s only LTE in 2023?
But on the other hand, I do always buy the cellular version of iPads even though I could just as easily tether those to my phone.
Autonomy - walk to the loo and your laptop continues doing it's thing instead of stalling due to the phone getting out of reach. It also makes the phone battery last a bit longer. Performance will be better as well. If you only use mobile data on the device every now and then a tethered phone is fine, if you use it all the time a built-in connection is preferable.
The ability for corporate IT to better control how their devices connect to the internet, and/or not requiring a work phone to be supplied.
I've seen issued laptops coming with cellular data + persistent tunnel as the default connection method over allowing use of client/public/site WiFi networks.