Merriam-Webster had to change their definition too, IIRC.

But it's because whoever does the CDC web site, and whoever wrote the Merriam-Webster definition, were laypeople and didn't get it quite right. Either that, or they tried to simplify the actual definition so it would be easier to understand for laypeople and didn't get it right.

In the end, you're cherry-picking incorrect definitions in order to make a point that's simply wrong.