If I understand correctly, having less leaves is just having less photosynthesis to provide energy for the plant. That said, if you have a determinate variety, stressing the plant by removing leaves could force a short-term focus on fruit development. However, I don't see how it's different from pruning a sucker, assuming you're not getting any fruit from it.

Something I've noticed that might add to this is that old leaves are sometimes used to different light conditions than new leaves (and this can stunt a plant until those old leaves are removed, the light conditions change, or until the plant gets quite a bit older). This is especially noticeable when transplanting (esp. watermelons with plenty of leaves). I'm not saying my Early Girl F3's leaves were like that, although they did fall over into the shade (my observations were with dramatic increases in light, and maybe in changes in what kinds of light are present; I'm not sure if it works the other way around).

I hypothesize that this might be the primary reason that watermelons seem to do better if you don't start them indoors too early (because they get more leaves that aren't used to outdoor sun, and it seems intuitive to leave them there forever). People think it's about the taproot, though. So, we would have to experiment.

Commercial growers do prune them, usually up to the first ripening cluster, and in some places (like Italy) even more aggressively, up to the first forming fruit. They don't normally do extra work unless there is a reason (one reason is that it's easier to harvest, another is that they have bare stems and can lower the plant down).

I haven't made comparisons, but there was this korean paper that compared various methods for max production and their conclusion was 'Therefore, the optimal leaf removal method is to remove all leaves until only one leaf remains above the truss where harvesting begins during either the hot or winter season.'