Your rule is a common one, but somewhat misses the point of the argument. In the absence of a CLA who does own the copyright to the work you do?

The point of the article us that it may, or may not, be you.

I notice that you weren't clear on this part in your post, suggesting perhaps that it's not something that's front-of-mind like the CLA is.

On the CLA front I'm on the fence. Assign, don't assign, that's for each person to decide.

But the alternative to CLA is not necessarily "I keep the copyright". That's the point the article is asking you to consider.

Aside; unless you have a specific bit of paper assigning copyright to you, and assuming you have a day job, it's very unlikely that you hold the copyright even if you only do OSS work at home on weekends.

And lastly - have you ever enforced your copyright legally? If you have never enforced a copyright violation then your work is effectively public domain. Yes the threat that you could take action exists, but in practice your contributed-to-project can change their license and call your bluff.