this
on my old comp it didn't even work so it didn't matter. and on that i lagged at 20k bricks
although yes, with any decent modern computer you shouldn't have issues, not everyone is tech-savvy enough or wants to pick a good computer based around how well it would perform when running blockland. and then there are the preteens/teens who don't have the $$ or the freedom to choose what computers they can use.
The performance of minimum compared to off seems to vary highly.
For me and many other people, minimum (as a reminder, this setting does not have shadows) run much much faster than the off setting.
But there has been a number of people who run poorly on minimum.