Did any manufacturer ever try using more, but lighter spokes to minimize weight?
To the best of my knowledge, and my ability to find reference in any old catalog or tech manual, no, that concept has not been tried on a commercial scale at least. It may have been tried on a local scale.

I don't have the math to prove it, but I suspect the balance point between how thin the spokes would need to be to reduce the weight enough to offset the additional weight of more spokes, and the tensile strength those spokes would require to maintain the strength of the wheel without breaking would prevent any weight benefit from being gained, and I know that spokes thinner than 1.8mm have a far greater likelihood of breakage. The butted 2.0/1.5mm spokes which were popular in the late 90's for XC racing wheels proved that to me.

Perhaps we could get the Math or engineering SE guys to comment here?