I don't know the veracity of this, but when I've seen concerns about this raised, usually it's mentioned that something that pours so much energy into the edible part for no reproductive benefit would have a hard time outcompeting something that doesn't do this.

> It's plausible that these hybrids would substantially outcompete the local flora

This is absolutely not plausible. It's also not plausible that high-yield broiler chicken would outcompete local birds, and it's not plausible that high-yield cows would outcompete local moose, elk and deer.

It is interesting that with animals, people intuitively usually understand that high yield food producing breeds would not outcompete anything in the wild nature. But with plants, people are ready to believe scifi horror movie stories.