At the end of the day, Trading Card Database encompasses more than standard-size trading cards. After all, if we stuck to just trading cards that are 2.5 x 3.5, sets like 1989 Bowman baseball or 1970-71 Topps basketball or 1965 Topps football wouldn't qualify - and it's hard to argue that those aren't trading cards. So, an exception (which is a word a lot of members don't like) was made. And then there were more things that came up and were deemed to be included or excluded. Seems like every week there's a new item that comes up with someone asking about it being included (as an aside, I think a list on the site of specific sets that have been deemed to not meet inclusion should be kept for reference, and a list of sets that do receive an exception from Admin would be helpful too).
While exceptions and criteria for inclusion have evolved over time, there are a few common underlying themes, and one of those is paper. Generally speaking, cards made out of just sheets of paper have not been allowed here. These include things like the sheet you bring up, or MLB all-star game programs. I can't say that I know the reason, but that has typically been the line in the sand for the last several years.
The truth is that the FAQ entry for "Other Collectibles" does say that items "... and authenticated by card grading companies are also allowable". But again, it's not black and white - there is a leading "and" in there. So, does that mean that items must meet all three of the criteria (made by card company, sold via card retailers, graded by grading company)? I would argue that the way the guideline is currently written, yes, all three criteria should be met. That isn't to say that it can't be interpreted the other way - that only one of them should be relevant (like in this case, PSA grades them, so check box #3). But PSA also grades MLB tickets - would one argue that they are trading cards as well? Probably not, and as collectible as they may be, so is currency and USPS postage stamps; both things that are beyond the scope of this site.
In all fairness to AlafiaRiver, this is not the first time they've brought something up with fair points and wondered about this, just to be told "no it doesn't belong" and that's the end of it. I'm sure it gets frustrating over time when that's the type of response that most of your inquiries get, especially when we're talking about something that isn't exactly clear, like why these wouldn't typically be listed. And when you're met with answers that sound strongly opinionated, especially time and time again, it can lead to frustrated replies. This is a forum, after all, where people can post whatever they want and discuss whatever they like as long as it doesn't go against forum rules - healthy discussion is good for all of us.
Jeff, I hope this helps a little with regards to including these here. I can't provide any help beyond the site's side of things, as early 1970s football collectibles are not a strong suit for me. As far as removing things from the site...remember, this is a crowd-sourced site. That means that in theory, a member of the site who has the appropriate permissions can create a set and add a checklist of whatever they like, however they like. No review process, no checks and balances, nothing. Some items, like postcards, have explicit rules in the FAQ, and yet someone can still add them however they please. As they are discovered, they are removed from the site with Admin's help since they blatantly go against the published guidelines. I have submitted IRs for sets before that I actually added when they didn't belong here - I was adding my collection, realized a set wasn't here, and added it before being corrected several months later. Sometimes they're honest mistakes; sometimes, it's just people who don't give a ... ya know, and just want to document any collectible they can.
Your best bet at this point is that if you feel strongly enough that they should be listed here, compile all of your supporting evidence (PSA, eBay, Google results, whatever you can find that supports their possible inclusion) and present them to Admin via a message. It's his site, and his rules, whether we like it or not. All I would suggest is that you remember that last sentence, and should he say "no", then there's really nothing else we can do.
I'll never quit collecting entirely, but I am downsizing. Check out my COMC store and help me thin out what I don't want so I can buy cards that I do want. See something you like? Send me a message on here, and we can knock the price down quite a bit. I'll even take a bit of a loss if it means getting you a card you really want.