A weird advice worm ate its way through the blogosphere in the late 2000s and early 2010s that made people think that if content was "evergreen," it didn't need a time stamp. The reality is that even the best advice has a context of time and place, and translating it forward requires knowing that context. Some people still follow that advice, or don't even know about timestamps and just grabbed the first theme they liked that didn't have them.

For example: so much advice in photography that gets repeated without thought is from a time when automation wasn't very reliable, or from the early transition to digital. So new photographers end up being miserable in full manual when they'd learn faster with a little computer help, or they burn $2000 on a lens they aren't skilled enough to use when their modern $50 kit lens is sharper than almost any of the legendary film-era lenses that didn't have to contend with 20+ megapixel sensors revealing all their flaws. Any blog post from the 2000s on the subject would have been mostly right back then, but without a timestamp, it's hard to know where it fits.