From their post mortem https://medium.com/@gabriel_20625/technical-lessons-from-bui...
> Performance is never a justification for anything if you haven’t measured it
This just isn't true. Anyone with a reasonable amount of experience is often able to look ahead - well before any code is written - and see how performance could be better if road A is taken instead of road B.
Its madness in that case to blindly choose a road without even thinking about performance - even if it is unmeasurable and in the future.
There's more in the same vein:
> Go back to step 2 and make sure you completely ignore performance, because you probably haven’t.
Now I have to imagine that these guys don't genuinely believe what they wrote - but in that case, ditch the words "never" and "completely ignore" and go for something more reasonable.
(Of course that would make the phrasing less dramatic and click-baity, which is maybe what it takes to get eyeballs these days)