You may be entirely right. But I wouldn't bet on that.
These days, teams in all sports typically want to know if their fans are enjoying their game day expereince. Besides wins and losses, do fans enjoy the stadium, are the hot dogs hot and the cold beer cold? Are they surrounded by loud, obnoxious drunks, do they have to stand in line to use the bathroom? Do they like the halftime show? Can they get in and house of the stadium facility with ease?
If the letter never gets to Irsay, that's fine. But I wouldn't be surprised if there is one person, maybe more, in charge of the "game day experience." That person works with the stadium and local authorities. I'd hope those people would get the letter. The owner of a successful company does not want to take their customers (fans) for granted. Especially during a tough rebuild period.
Just a different perspective....