This is unfounded in practice. Having a BDFL did little to stop Python's feature set from growing, or to prevent design flaws like `lambda`, or to make Python 3 anything other than the poster child for how not to break things. Conversely, we can look to Javascript (yes, Javascript!) as an example of a language that was a total mess after being designed by a single person and that got immeasurably better once it began being designed by committee (yes yes, "ten days" and all that, but I daresay that even Eich would agree with me that the Javascript committee has done a relatively fantastic job).

The reality is that languages are born with a single creator, and spend their adolescence growing under that creator's care, but achieve maturity once they can demonstrate that they can function without such a single point of failure as a BDFL.