It's also interesting to see the age-old functional programming problem: you trade performance for ease of development. I think these days people assume that things like immutable data structures are optimised under the hood. That doesn't seem to be the case with React, as you have to explicitly use a performance trick everywhere.
Their argument that it would be premature optimisation to think about where memo is not needed makes sense, it's an interesting shift of optimisation of the runtime performance vs optimisation of the dev time.
> Using memo and its cousins everywhere is a sane default. It’s like a mask mandate during a coronavirus pandemic. Sure, we could have everybody tested every day and only ask people who are actively contagious to wear a mask. But it’s far cheaper, simpler, and ultimately more effective to ask everybody to wear a mask by default.
That's a good metaphor. It's easier for the people who decide, by shifting the burden on everyone else. I personally get headaches by wearing a mask all the time at work. I think I may get headaches too if I had to remember something like this all the time.