When a discussion about a cut-off date for a U.S. collection turns into comments about people on stamps you don't like, stamp collecting starts to seem like the old and cranky hobby a lot of non-stamp collectors think it is. I have some Hitler stamps in my Germany collection. Is that okay? And how about those Mussolini stamps? And Juan Peron and Francisco Franco. Some Mongolia stamps show Genghis Khan, who may have been the world's #1 mass murderer as well as a rapist, on its stamps. I have Stalin stamps I don't like, but there they are. Lots of stamps have subjects we might be offended by. Collect them -- or don't collect them. It's entirely your choice. As for Janis Joplin, she was an extraordinary singer who appealed to millions of people and like millions of other people, also had an alcohol problem. Are alcoholics banned from stamp collections now? I've got news for you -- better get your album out and start removing a lot of stamps.
As for cut-off dates, there's clearly no "best" date, as the evidence here shows. Each person has their own reason for choosing a date. Some years back, I used 1990 as my cut-off date (before most self-adhesive stamps and the flood of mini-sheets), but now I don't have any date. I collect modern stamps I like and don't aim for "completion" at all. I don't have a cut-off date. Well, I sort of do. Maybe 2010 now. But maybe that will get moved up eventually. The only reason for a "cut-off date," as far as I can see, is that you have a collection dictated by the album you use. If you don't do that, you can add whatever stamps you like. Add blank pages -- or make your own pages. Problem solved. Drawing boxes on blank pages isn't that hard to do. Or use quadrille pages. Plus, you'll end up with a more personalized collection in two ways - your favorite stamps and your own page layouts. That's kind of cool and it's much preferable to printed album pages, in my opinion.
As for alcoholic rock singers and drug addicts and other awful people:
Elvis had a drug problem. Billie Holiday had a drug or alcohol problem, too. JFK had sex with women who weren't his wife and regularly took drugs for his Addison's disease, so he's out. Harding clearly had a drinking problem-- and a womanizing problem, so he's out. Ronald Reagan completely ignored the AIDS epidemic, broke the law very badly in the Iran-Contra Affair, and tripled the federal budget deficit. So his stamp is out. Nixon was a liar and a cheat. So his stamp is out. Eisenhower had a girlfriend outside his marriage, so his stamp is out. Jefferson owned slaves. Out. The United Confederate Veterans stamp honors traitors. Out. Judy Garland was an alcoholic. Out. The Breast Cancer semi-postal stamp has the word "breast" on it. Out. Paul Robeson on the Black Heritage stamp was a communist. Out. Malcolm X. Out. The Dr. Seuss stamp. Out. Did I mention Elvis had a drug problem? I'm joking (needless to say) but politics or social shaming -- or whatever this is -- does not go well with stamp collecting.
A couple of times at stamp shows (remember stamp shows?) I heard a dealer ranting about some political issue or person they disliked. It's completely inappropriate to do that with customers. As my Daddy used to say, "Son, we don't talk about politics, religion, or sex at the dinner table." It makes stamp collecting uncomfortable. Political views are out of place at a stamp show, so I just get up and leave. If you want to ruin stamp collecting, this is how you do it.
And while I'm my soapbox, people do make this claim a lot, but the U.S. government does not issue stamps in order to "fleece" collectors. The income they get from stamps purchased but not used is pretty small. Stamps are issued to appeal to the general public, to honor people and events, and to appeal to various interest groups and others so they'll buy and use stamps. The postal service may or may not want to accommodate the needs of collectors, but since they're a business, that's their choice. In a nation of 330 million people, issuing lots of new stamps every year doesn't seem all that surprising. It's maybe just a few too many, though, I admit. Have you ever looked at the number Japan now issues every year? Now there's a postal agency which needs to develop some self-control.
I don't know what the claim that collectors have "supported them virtually from the beginning of the issuance of stamps" means. Collectors were not lining up to buy the 1847 stamps. And in the early years -- like today -- the Post Office Department depended very little on purchases made by stamp collectors. Unless somehow has evidence to the contrary? There have been some stamps issued which seemed mainly to appeal to collectors, but I'm not sure you could "prove" that. The high value Columbians were pretty silly and so were a few others. But these are the exception, not the rule. Today's high-value stamps serve a purpose -- Express Mail packages. Why would anyone feel obligated to "spend several hundred dollars on new issues each year"? No one's making you do that. Stop it.
As for stamps you buy "may never increase in value . . . ," where does it say they're supposed to increase in value? How many sheets of 3c commemoratives do you need to own before you realize that, beyond the inflation rate, most stamp values don't increase much? If that bothers you, stop buying them.
Now if you'll excuse me, I have to get back to supporting the U.S. Postal Service by working on my socially and politically-approved stamp collection, all of which were purchased so they would increase in value. Actually, that's another way you could collect stamps, isn't it? Just leave out all the stamps you dislike. If that's what you like, go for it.

No Marilyn Monroe stamps, though. She died of a drug overdose. The 1948 Poultry Industry stamp is okay, though.
