That post is so abbreviated as to be wrong in a few places (for instance, it's not that your "HTML" needs to be under 14kB, the packet, incl. headers needs to be). Fuller link: https://www.tunetheweb.com/blog/critical-resources-and-the-f...

It's not worth chasing except for personal curiosity and some truly extreme cases.

The response needs to be. The response can span several packets, up to the maximum receive window chosen by the client's OS.