A neat little idea that reminds all players that being the DM can involve a lot of effort both at the table and outside of the 'contact time' - preparing adventures (whether sourcing published ones and reading them or making up your own), reading about the setting, researching stuff, getting resources like maps and handouts ready...

For many years, the local group has ended with the DM thanking everyone for playing and them in turn thanking the DM for running the game. This card just takes that courtesy to the next level.