I don't think that judgement is fair. 'Badly coded' is not the same as when a developer lacks the understanding needed about the rendering engine. I do however agree on your sentiment that it's not the browsers fault.
Also, sometimes you need to pull back on resource-heavy design decisions if they're hurting performance.
It might have sounded harsh and I agree that it might not be fair, but if you lack understanding you will write "bad" code. It doesn't mean you can improve or be taught to code better.
I don't think that judgement is fair. 'Badly coded' is not the same as when a developer lacks the understanding needed about the rendering engine. I do however agree on your sentiment that it's not the browsers fault.
Also, sometimes you need to pull back on resource-heavy design decisions if they're hurting performance.