I think that the market for smaller phones has died a bit as phones have become the primary computer for a lot of people.
There are people who don't own a desktop or laptop at home, or if they do, they use it very rarely. For them, their phone is their primary device, so it makes sense for the screen to be large enough that it's practical and comfortable to use for long periods.
Yup since OneNote has became really good, I find myself nowadays predominently going to meetings with just my phone and no laptop or paper notebook. What would be amazing is a way for easily connecting phones to HDMI.
I see others using tablets with a keyboard or the surface pro with a stylus but I don't like the form factor which I have to carry in my hand but not in my pocket. Considering a switch to Samsung Note 9.
There are several ways to connect phones to screens. Android support screen casting to some smart TVs like LG (I used to use this feature all the time and it works really well over WiFi). Unfortunately Apple does it's own thing so you'd need an Apple TV if you want to use AirPlay on iOS.
However iPhones (and some Android handsets too) do support HDMI over their data port. You'd need to buy a cable but they can be got for ~£15 (though you'd be looking more at £40/£50 if you want an official branded one - but I've found 3rd party dongles generally work just as well on iPhones).
I switched to a Note 8 from a Nexus 6P for the stylus.
I probably use it once a month. The input latency and the small size (compared to a notepad) prevents it from replacing the spiral notebook I carry.
I also understimated how much I'd hate the samsung crap that's installed, and the edge to edge screen is more trouble than it's worth--I'm always accidentally clicking something while holding it.
There are people who don't own a desktop or laptop at home, or if they do, they use it very rarely. For them, their phone is their primary device, so it makes sense for the screen to be large enough that it's practical and comfortable to use for long periods.