Opinions differ on CLAs. There are certainly arguments for them as laid out in that article.

There are also arguments against them in many cases, including that they create friction for new contributors. "Oh, I have to sign this agreement which means talking to my company's legal staff? I think I'll just pass."

The parent is also probably right that GPL with no CLA makes it much harder to change a project's license. This actually came up when GPL v3 was released. As it turned out, Linux apparently didn't want to change Linux from a v2 to a v3 license. But there were also legal questions about whether he could do so by himself even had he wanted to. (Though Eben Moglen argued at the time that he maybe possibly could have for various arcane reasons.)

ADDED: I recorded a podcast on this and related issues recently: https://podcasts.apple.com/us/podcast/open-governance-chris-...

A CLA isn't necessarily a copyright grant. The Apache one for instance doesn't have you assigning copyright to the Apache foundation. It's just signing that you actually own the works in question.

I have issues with the GNU assignment. It means that we're reliant on future owners of the GNU project to not ever relicense the codebase. A single owner is a single point of failure.