What is this called (Dash seal???) and do I really need it?

Damn your dating yourself sir! Back in the 80’s we would do PDI (pre delivery inspections) when I was a dealer tech on the new cars. We would find everything from matches to newspaper to cardboard. Heck I even found a tool blocking a hole then body puddy over. Back when if a sheet metal part was punched wrong they still used the part and filled in the gap with what ever the line boss had at his bench.
I remember stuffing a pack of matches under an 8 track to make it play better.
Am I getting old or what?
lol