>It's kind of weird to me how programmers (especially of libraries like that) aren't more careful about introducing breaking changes, since the work needed to be done afterwards multiplies really quickly.

Programmers, generally, always aim to do that.

But the JS framework world for whatever reason has this constant obsession with reinvention. I honestly think it stems from a sort of inferiority complex that FE devs had in the the 2000s/10s which led to every single library feeling the need to invent new words to describe some CS concept that has been around for 40 years, and to massively overcomplicate things for the sake of sounding smart. So stores became "reducers", promises became "thunks", and macros became "runes", and lots of FEs got to high five themselves and add that stuff to their FAANG promotion packets while we wallowed in their mountains of meaningless abstractions in the name of "doing things The Right Way" like FB and Google.