Article lost me at the phrase "could care less".

I don't think it's about having more space necessarily—just having higher pixel density looks nicer?

I dunno, I use a Dell 4k pretty much every day and I find it to be absolutely fine? I can't check right now but I believe I use the scaling option that makes everything a bit bigger and I got used to it pretty quickly.

Literally no good reason to scroll horizontally.

Agree with this 100%. In programming terms, this is known as 'composition' and it translates very well to design, especially within a design system based on components.

This looks pretty nice but many of the components (accordion/tabs) aren't accessible.

I review the PR in Github and leave comments as I would also do for a code review. I can also pull the branch and make changes myself. Luckily, I sit next to them so can also provide feedback in person but I think everyone finds it helpful to have feedback documented in a PR so they don't miss anything.

I don't see what problems an iPad solves for these tasks? I'd stick to a laptop, they're just as portable and you'll have way less problems.

I think it depends. Are you drawing pictures of websites/apps for stakeholder approval and then handoff to devs or are you prototyping/testing/iterating more complicated apps for testing with users? If the former it's not so important.

I think not only state but a layout model that mimics (or is built on) the same layout model that the platform you are designing for uses. An obvious example being HTML/CSS and the box model, etc. with breakpoints.