LOL. In some situations, it may be more positive for the growth of bad plants than of good plants, thus, may harm the good ones in the competition. Fine, you have found an exception. Now you summarize this, and it looks like 33% positive, 33% neutral, 33% negative. And that's why the mass media can present this as 99% negative, simply because the remaining 66% are not that interesting for the readers, we suppose. I have. If there are a lot of very different, independent plants which compete, and every news may be 50% positive, 50% negative (because the direction of the change is yet another independent variable, and if one direction is negative, the other is positive) then I can expect a balance. Of course, there is the correction, namely that every big change requires costs for adaptation, thus, has a negative aspect in above directions. And, then, a single question may be the decisive one, making all other news simply uninteresting in comparison. On the other hand, if a weed obtains greater advantages than a useful plant, this may harm the crop in wild nature, with free competition, but not in agriculture. An out of context example. But what is waste for humans is not necessarily waste for animals and plants. Remains of sunken ships are in some areas full of life, while their "clean" environment looks like to a desert.