Boards take up a lot of room on the water. If you get six boats running 3 boards on each side on smaller lakes (under 500 acres), then the lake is pretty much locked up. Add a few ski/pleasure boats in there and now you have issues.
If one wants to fix the problem, you guys nailed it. If you want to troll, you get one rod each. Now you don't need boards, or if you do run one, you aren't taking up much room.
But I've heard from some old timers up north that trolling was made illegal because it was just too each to catch big fish and it put a strain on the lakes. I'm guessing that this wasn't a good thing because those lakes up north are already pretty strained from the spearing that takes place.
But I digress. When backtrolling was allowed, it was so walleye fishermen could position their boat in the wind without anchoring. It was meant for boat control, not bait presentation/movement. Muskie guys figured out quickly how to backtroll their baits with great results and boom, no more backtrolling.