Print Shop became a killer app for home computers for the other reasons the article discusses: Custom posters, signs, and banners, the things not readily available at retail.
and so many "keep out" signs for my bedroom door (with the skull and crossbones clipart and their Thames font because it looked pirate-y)
as the son of a Print Shop addicted mother through the early 90s, you've believed wrong.
It was pretty empowering for people to be able to customize things. Oddball holidays or festivities that major labels would never touch. Niche topics that were kind of controversial -- it happened at a perfect time when desktop printers became kind of universal and multi-talented.
It's hard to find a "Congratulations on the vasectomy!" card at Hallmark. Print Shop made it not only feasible as a one-off gag, but easy.
We used it extensively in the 80s for birthdays, Christmas cards and more.
Anything made by computer was instantly special, and the ability to customize card to the recipients interests was viewed as magic.
As more of our neighbors and friends got computers, print shop was one of the first programs to be acquired. (Okay, often pirated!)
Oh boy, you've got a fun education ahead of you today!
See
https://en.wikipedia.org/wiki/Symbolic_capital
E.g., mom tells a relative I want to make a card on my computer for them, then tells me they'd really like a card made on the computer. Yay, they need my skills to make them a card.
I'm not sure symbolic value includes the joy my mom got from being a kind of P.T. Barnum of my card-printing skills (and card folding-- 2 ply IIRC). But there's that, too.
Anyway, that Wikipedia article will unlock a lot of cool new areas and skins that you can't get without it.