If you are on HN, you likely use a computer a lot. But 15 years ago, a switch occurred, and nowaday, there are way more people using a phone that don't have a computer at home, or use it rarely.
This means for the vast majority of people today, and hence customers, the phone IS the computer. It's the entry point for everything.
They consume content, shop and even work on that.
But phones have terrible ergonomics. Their productivity sucks.
One of the reason is the limited screen space.
For someone using a phone, mostly as a communication device, while doing important things on a computer, a small phone makes sense. I'm this kind of person. My phone is too big for my taste. Anything complicated, I reach for my laptop: it's more efficient. Phones are terrible at multitasking, and constraint myself to 2 finger typings, tabs that open in several steps and a viewport of the size of 2 credit cards?
But we are not the target.
For the target, a big screen is the mandatory crunch they need because they watch a lot videos, do banking, read pdf and even type work stuff on their phone. This tiny, constrained square they have to make do with for everything.
It makes small screen a hard sell. The iphone mini was not a great success if we compare it to other phones, despite everybody claiming we would all love it.