Probably true, but as the article suggests, it may be more than just exercise. Some people seem to be given a creative brain from the get-go, whilst others must work very hard to produce creative outcomes, and indeed...may stop trying altogether because of this.

If I take the least creative people in my circles, one pattern I can spot is that they lack curiosity. Interests are narrow, shallow and for pragmatic reasons only. Not ignorant, just cognitively passive. My pseudo-scientific take on creativity is that it's connecting dots in unforeseen ways. Without curiosity though, there's little to connect.