Transmission losses aren't a big problem for the grid precisely because we know we will have transmission losses, so we don't do things that will incur unacceptable losses.

The whole "plate a desert with solar power and solve the world energy problems" doesn't work because the desert isn't where the power draw is. Superconductors hypothetically permit the African desert to supply Europe with power.

As this goes from science to engineering, we may find other issues with that plan, beyond the obvious expenses (for example, current limits can be handled with more wires, but if the current limit is sufficiently small that's still a problem, this is no solution if the superconducting bundle has a hundred square meter crosssection), but superconductors at least put it on the table. Conventional conductors do not.