Why not? If biwiring did anything, I could take a great big amp with some fat cable and put a splitter halfway down the line that split it into two smaller gauges going to each terminal set (hi and low) and be better off than splitting it right out of the amp.

Now as to whether the signal is summed internally and then split to each part of the crossover, you'd have to ask the speaker manufacturer or take them apart yourself. If the terminals can take jumpers externally, then the summation probably doesn't happen. If it does not take jumpers then the speaker either must be bi-amped or the jump is done internally thereby summing the signal and splitting it.

We should disregard monetary aspects, as in for the money. That can be worked out after getting the theory straight.