> With thousands of geometries in an interactive map, with lists and tables of items filtered by bounding box and categories, sorted by geodetic distance from wherever you were interested in, the performance issues that arose were never too many uses of useCallback or useMemo. The opposite caused issues multiple times however, of the app running haywire (or to a halt) kind.
The author here is taking their very valid and necessary use case for the optimization of memoization - non-trivial and expensive operations - and extrapolating from that to "just use useMemo, it's a best practice". Memoized functions are more complicated to reason about and therefore more bug prone than their alternative. Most client-side apps don't have thousands of records they're iterating over, they have dozens. Throwing around memo because one might one day become big, and you'd pay some performance penalty, doesn't seem prudent to me.