Question about signaling on the TGV.

[Class325Guy]

So I know that on the high speed sections of the lines instead of using normal signals they use boards to show where the blocks are because normal signals would be too hard to read. Of course that sorta make sense, but how are the boards any easier to see? Since you have in cab signaling, wouldn't it still make sense to have some type of lighted signals to at least mark where the blocks are?

I don't really know that much about the TGV but like to drive it in Train Sim.

Thanks