The article is about how Apple is underdelivering in browser features and compatibility while pretending they aren't. It's about Apple. Apple. The ones responsible for a great many features not being supported in all browsers.

What does a web dev have to do with Apple's choice? How do you improve Safari by not using features it doesn't support? What does your comment have to do with the argument the article is making?

You appear to be arguing that we shouldn't care that Apple provides a consistently bad experience and locks their users into it, because web developers can level the field by degrading everyone else's experience too. There's a nice couple paragraphs in the article that explain why we should in fact care, and you don't seem to have addressed them, so let me reproduce them for you in case you missed them. (also, you might not be aware that "it's not that hard, ask your LLM" comes across as incredibly rude and snarky.):

These large, persistent gaps matter to the mobile and web ecosystems because Apple is unique in denying access to more capable, less-buggy engines and actively erecting unlawful barriers to choice when forced by legislation to enable it. This is accomplished through eye-watering budgets for legal shenanigans, direct lobbying, and well-heeled astroturf front groups to maintain a capability gap between web and native.4

That chasm is instrumental in trapping users and developers in the extractive vice of Cupertino's App Store. A persistent, material gap in capabilities creates a perception of the web being less-than; a budget option for the unserious. Should users choose more capable, more private, less buggy browsers for a larger share of their computing needs, Apple might lose the leverage that enables it to extract rents.