According to wikipedia [0], such a device was actually proposed by a priest in 1754. The theory was more or less as you describe. But there is debate on whether

According to wikipedia [0], such a device was actually proposed by a priest in 1754. The theory was more or less as you describe. But there is debate on whether it counts as a lightning rod, and apparently most lightning protection systems work exactly the way you said they don't: to provide a very low impedence path for the current to go safely to ground, which is called a Franklin design. [0] https://en.m.wikipedia.org/wiki/Lightning_rod#Europe https://en.m.wikipedia.org/wiki/Lightning_rod#Europe