This statement strikes me as ignorant even if we talk exclusively about Tesla. The idea that Elon hasn’t improved on existing designs across all of his current companies (or Paypal) borders on indefensible. Reusable and landable stage 1 boosters come to mind.
It's odd people bring up PayPal as a star on Elon's resume.
a) PayPal, especially in the early days, was near universally reviled. It was sort of what we were stuck with.
b) Elon became part of PayPal in a merger, and was later removed as CEO.
I think some of these people believe Elon is personally designing and engineering these things, so naturally it carries over.
Gwynne Shotwell doesn't get enough credit.