If you want acceptable performance in a reasonably complex react app you absolutely have to memoize. The fact you think this isn’t the case suggests to me you haven’t worked on a big react app.
There’s a significant difference between having to memoize and having to memoize tons of stuff.
Generally you should only need to memoize a few things, and if you find that your app becomes brittle due to the amount of memoization you’re doing you probably are not handling state in the right way. If you’re using Redux that’s a common reason for this; don’t use Redux (is my advice). And yes, I’ve worked on several large enterprise React apps at successful startups.
