I didn't specify which keyboard. Even mechanical keyboards can be affected by this. I wasn't referring specifically to the new Macbook butterfly keys.
Most mechanical keyboards are basically protected from dust entering the physical area of the switches due to a hat-like dome formed by the keycap itself. On top of that a lot of the switches are closed and rated for minor dust exposure (cherry's can with stand some water and dust internally)
I've never heard of a keyboard failing because of dust with the exception of Apple's MBP keyboards.
But that is not the problem. The problem is really that the keyboard is susceptible to a problem that 99.9% of other keyboards are not, even on laptops.
A complete failure of operation because of dust is inacceptable on a device that will be expose to a lot of environmental dust from being in laptop bags or having people carry them around to eat or similar.