Why so many electric fans???

['68 Newtricks]

Putting my truck together and plan on running an LS/4L60. Its mostly just a rolling frame right now with some CPP engine and trans mounts ready for the combo.

My question is:
I want to run a mechanical fan for simplicity. This will be my DD, and like my offroad blazer I want it super simple. Why do most swaps end up with electric fans? Is there fitment problems? I hope to run the stock shroud or something close. I also don't have a problem moving the combo back in the frame as much as possible, since I like the idea of moving the weight and I don't have a driveshaft to match anyway.