> Custom fonts are a waste of bandwidth
Latin subsetted fonts are generally 10-30Kb, it's really not that much. For comparison, it's unlikely you'll see blog authors get up in arms over a single PNG.
> they come with one of three evils called latency, FOUT, and FOIT
A few milliseconds of a different font appearing is truly not much of an evil, but can be addressed by exactly what the author links in their footnote.
Humorously, the author's own site is committing some sins here: both of two font files are >140kb, they don't have gzip on, and they have the fonts marked `font-display: block`. They could cut their CLS and LCP by almost 100% by addressing this: https://i.imgur.com/MOl32iS.png
Of course, it's already very fast, by virtue of having no other resources loading. This would be dramatically worse if there were scripts that needed to get downloaded.