Sorry Kathy, but I'm having difficulty answering your question.
If I take your question as you mean it, I would say there is nothing 'wrong' with radishes which do bear 'fruit' as in the roots swell enough to be enjoyed in a salad.
You'll have to tell me if that is close or otherwise to what you mean about weeds.
Do you mean also, that in general, weeds grow like crazy but never bear any fruit?
If so, what about the humble blackberry vine? Grows like crazy, is a horrible 'weed' in the garden and very difficult to get rid of, because the roots are buried deep in the earth and produce new roots easily.
Other kinds of weeds, for example the dandelion, produces roots that can be roasted and then ground into a coffee-like' drink, along with the leaves, when young, which can used in a salad. There are many more 'weeds' which can be used for culinary purposes.
Wild fruit grows on the various wild trees as well as the common wild strawberry and raspberry and bilberry etc.
Does this answer your question or am I off the track?
You'll have to tell me, because I'd like to know.
Thanks for the question.