I guess for many places it was simply that food supplies were never that plentiful, so it's worth the risk to try and make safe something that looks like it could be edible.
If your food supply is plentiful there probably wouldn't be the same incentive. But for most people, for most of human history food has not been that plentiful, so any extra source would have been welcome.
This is probably also true of all the ways we've found to preserve food. When you know the winter is going to be lean it's worth experimenting with things to see if you can eek out out supplies of that little bit longer.
Apart from scarcity, I wonder what it was about dishes like Fugu[1]. Maybe every fish didn't kill everyone all the time, so the element of danger added to the intrigue, etc.
If your food supply is plentiful there probably wouldn't be the same incentive. But for most people, for most of human history food has not been that plentiful, so any extra source would have been welcome.
This is probably also true of all the ways we've found to preserve food. When you know the winter is going to be lean it's worth experimenting with things to see if you can eek out out supplies of that little bit longer.