If you have enough abstraction (like with the web) and understand basic performance principles, like instructing the computer to only do, what is neccessary, then one doesn't need to understand the system beneath, to get performant code.
It is mostly enough to know that method A is expensive (e.g. drawing a big image) so if you avoid it, than this what brings you good enough performance.
So sure, no one is talking about high performance low level graphic engine code. For this you clearly need to understand the bare bone metal interface.
And of course the baseline is pretty low these days. The ordinary web is full of horrible inefficient ways of doing things, so you are probably already above standard, if you avoid the worst habits..
It is mostly enough to know that method A is expensive (e.g. drawing a big image) so if you avoid it, than this what brings you good enough performance.
So sure, no one is talking about high performance low level graphic engine code. For this you clearly need to understand the bare bone metal interface. And of course the baseline is pretty low these days. The ordinary web is full of horrible inefficient ways of doing things, so you are probably already above standard, if you avoid the worst habits..