Isn't allocation the only unseen part of construction ? Everything else is visible in the code and surely a few assignments are never expensive. Any other expensive operations will stand out in measurements of code execution.
That's correct. However, the article seemed to shout "Don't worry about creating as much objects as you want", which I wouldn't support if taken literally. You are right that proper tools should uncover any additional overhead though.
Moore's law is another optimization we sell in advance all the time.
*bg* Twenty years ago, I had to work on a 8008 driven computer with 4k RAM and 12k ROM. That's enough to run a program which nicely prints formatted and justified text (25 lines a 80 characters). We went a loooong way since then.