It's gotten to the ridiculous state where common phones will very often have more screen resolution than 14'' laptops. So as long as you have a way to comfortably stand close enough you won't be lacking for pixels. Eye strain from focusing that close will probably be higher though.

But in this case, they just have a low resolution phone, AFAICT.

This is clearly an extreme case, and quite impressive. I was commenting on the general case of developing on a phone screen. 2300x1080 phone screens are now on ~200$ phones, while getting more than 1920x1080 on a 14'' laptop is difficult and gets you a "why would you even want more than FHD on a 14'' laptop" comment consistently. At least 16:10 is now becoming more common so 1920x1200 is growing a bit.

Aren't there already many folks looking at their smartphone screen for significant amounts of time every day?

actually working on tiny screen is not that hard tbh. When my macbook was under repair I used to use microsoft rdp to connect to other pc.

The good thing is i can use external keyboard and mouse. And screen was somewhat okay. The only issue was battery as I keyboard + mouse drains battery a lot.