Sure. But the amount of channels gives an indication on the potential users. And it's way way less than on the main network, basically a footnote at this point.
Yeah it _might_ grow in the future. But until it does it doesn't work as an argument.
Also in order to get into Visa levels of efficiency one would have to have (assuming the 741kWh in the main network) 500k TX per second in the lightning network with 0 energy cost. Visa handles around 1700 per second.
So basically if we'd have all the worlds economy in Lightning network we might get close to those numbers (assuming 8 billion people each doing one transaction per 4 hours, that's super high but ah well, whatever). And that's assuming the mining energy consumption doesn't change at all which it definitely would not do in case of the whole world relying on Bitcoin.