400' isn't that far. I can walk it no problem.
It's not that far past the fence. I haven't seen it very often with stock equipment and temps over 50, but I have. It's 70' from home to first, so it's about 10 steps past that over the fence.
The problem is people can hit a ball that lands about 30' past the fence, and they assume that on their very best shot they can at 70'. That's not the case. You probably just hit your very best shot, and with a howling tailwind you might reach 350, but they don't get that so they think their lie of 400' is plausible.
Depending on how quickly a ball gets out 330' can still seem like a bomb, so I'm cool with that being my goal.