Two things which most people don't realise about ESD:
- it's possible to have an ESD event occur which is not felt, but which nevertheless contains enough energy to damage a sensitive device, and
- ESD damage often doesn't mean a device fails immediately, but its lifetime and/or operating performance can be severely degraded.
This is a big deal, because it means people can handle boards badly, and remain blissfully ignorant of the damage they're doing because they don't feel or hear any sparks, and the board still works afterwards. "Therefore", the deeply flawed logic goes, "no damage has been done, and ESD isn't that big a deal".
Many years ago, when I was the hardware guy in a room full of software engineers, people would occasionally hand me boards and complain that they "just stopped working". For some reason they expected me to care, or to do something about it.
I did. I ordered up a big roll of ESD matting, and cut everybody a sheet to cover their desks. I fitted earthing studs, connected them up, and provided everyone with a wrist strap. I also sent out an email to all staff, explaining a bit about ESD and why it was important to use the equipment which I'd provided.
It didn't go down well, but that didn't matter. What did matter was that nobody ever handed me a board again which "just stopped working".