Low powered android devices are a thing. Networks outside of Metro US, EU, and parts of Asia, are also a thing.
Check out google maps there’s more to the world than your open office.
1. Even those low-powered Android devices are basically supercomputers
2. The Javascript bloat hurts those devices immensely. See "Performance Inequality Gap 2024" https://infrequently.org/2024/01/performance-inequality-gap-...
His point isn't "network/hardware is fast, so let's be inefficient": it is the opposite. "network/hardware is fast, so why is the page still slow?". On lower powered devices and slower networks, it's even more vital to author lean applications and web pages — but "things are slow even when the hardware and network are fast" is a simple canary that we are swimming through some problems.