I would love it if I could over-withdraw money from my bank account by having someone on the other side of the country take out money from my account at an ATM at the exact time as me, due to the fact that the bank's storage system was eventually consistent, but that's not the case.
I agree with you, but you are omitting a key aspect of the problem which makes this hard. If you have a single server serving from a local sqlite database, caching and invalidating the cache is trivially easy.
It becomes way more difficult when you have N servers all of which could potentially serve the same data. Local caches could then, yes easily become stale, and even if you have a propagation mechanism, you couldn't guarantee against network failures or latency issues.
But suppose you have an HA redis instance that you store your cached data in. Even with a write-through cache, you basically need to implement a 2-phase commit to ensure consistency.
People probably said the same about the horse and buggy when the car was invented. Not that I'd personally like a shit ton of social media buttons, just sayin'