It's still present. JSON/JS parsing still has a delay. And in either case (as the author states) not everyone is using an iPhone over 5G. Heavy React apps are a miserable experience on low end Android phones, even when the connection is fast. I've seen JS/JSON parsing times in the multiple seconds.

You don't think there's any palpable difference as long as the connection is any good?

Salesforce and SAP are not fast, even on that. But ubiquitous for building corporate platforms for their customers.

The vast majority of global users are not using iPhones.

Read the article. Typical users had old browsers often with poor reception. One user was using a PlayStation Portable which had very limited WWW capability.

"What, support Safari? Isn't that, like, less than 20%? And its standards support is abysmal! No, not worth my time, they can upgrade to a normal browser like everyone else."