If we’re both looking at the same article, I suspect it was written a while ago when the PD for F2A wasn’t current:
“Here's the general rule. If you want to adjust your status, you need to be in valid immigration status at the time of your adjustment. In a situation like this, Maria would need to maintain her student status throughout the time the green card case is pending. The reason for this is that there's a backlog on the processing of green card cases for the spouses of green card holders.
I know that sounds a little bit confusing but, basically, there are a limit on the number of green cards that are available in all kinds of green card categories, and that includes green cards for the spouses of green card holders. That is lawful permanent residences, husbands or wives.”
https://hackinglawpractice.com/can-my-spouse-adjust-if-i-am-an-lpr/
To me, it sounds like since there currently is no limit for F2As, they then can adjust. In the future, if it is no longer “current” then those people wouldn’t be able to adjust.