Well for the information to be useful there needs to be a scientific study done, along with everything that entails, before the data is meaningful. This kind of reporting is thin on facts and long on subjective assumptions.
For instance, what in their opinion constitutes "heavy" use? Are they talking about a couple of grams or 2-3 times that much?
What type of cannabis product is being used? Buds come in lots of forms, imported or locally grown, commercially or organically produced, bud, hash, extracts???
Frankly, I've smoked "grass" since the mid-70's and while not constanly, nor am I a heavy smoker, I've known plenty of people who were and I never in my life have heard of any such health issue. Of course lots of pot smokers also smoke tobacco, as well as those who have other health issues that might be exacerbated by pot use. Imo this definitely smacks of propaganda, and of course the news media has lowered their standards on reporting facts in favor of sensationalism just to grab clicks and eyeballs.