Don’t get me wrong
There are folks who paddle that way still, and have done so for many years. Most of them are probably much better paddlers than I am. Like most of paddling it isn't "wrong" in the way that means bad. It's just that, as more people have entered the sport, it's been found that a less rigid approach to holding the paddle seems to do better at preventing injury.
There's a lot more "try this" than rigid ways to do things as you deal with more experienced paddlers. Just as an example, within a year after I passed my 3 star I turned around and found that there was a quite different way to think about positioning the upper hand on things like a bow rudder showing up in in classes. The whole thing about edging, when I was first taught, emphasized lifting the upper knee. But in the last couple of yers I've yeard a lot more emphasis on weighting the lower hip.
In the end, you are doing both of the above for a good edge. But the way to think about it has changed.
I guess the best advice is, if you are going after training, be prepared to hear different approaches to the same thing and sort them out.