If you turn off any manufacturing line, your company forgets really quickly how to make what that line made. GE discovered this when they tried to restart a water heater line in Appliance Park.
We as a global civilization are close to forgetting how to make CRTs. There's like one company that still makes them, but only for military or major industrial applications (fighter jet HUDs and the like), at call-for-pricing prices. The major manufacturers, like Sony etc. all shut down their production lines, never to be restarted again because the knowledge of how to make them dissipated with those production lines. If you're an enthusiast who wants to experience retro video games as they appeared back in the day, your only option is to scavenge an old TV from somewhere.
Also since Sony shut down Walkman/Discman production it's now impossible to make good portable tape or CD players. The ones made now are huge and low quality.
FOGBANK was a little more complicated. The process that was written down just didn't work as expected. That was partially lost institutional knowledge that had never been recorded, but the original manufacturing just didn't understand their process. The process had contaminants improving the final product that they were unaware of. When the process was restarted, that didn't happen until it was investigated.
If you turn off any manufacturing line, your company forgets really quickly how to make what that line made. GE discovered this when they tried to restart a water heater line in Appliance Park.