My sympathies for lightweight rowing are well-enough known.
Lightweights can certainly compete with heavyweights.
Individual lightweights can win seats in heavyweight crews, and lightweight crews can defeat heavyweight counterparts. There is certainly a legitimate argument for saying that the little people should suck it up and play with the big boys. I think that argument misses the point. Lightweights often get lost in the heavyweight world. Many potential rowers are turned away before they ever get going because of their size.