So do I. As a matter of fact “To Whom it May Concern” is one of the last places you ever see the word “whom”. I’d forgotten about that.
I can easily count the people I know who still use that phrase in correspondence. There are people who abbreviate or shorten every other word in e-mails, as if they are texting, and have limited space-I always want to highlight every “RU”, “CU” “WTF”, and send it back to them, with everything written out.