This is only true when there is some context establishing recency. If I mail you a letter, that is recent and may be assumed to be in the current year. If I find a letter in my grandparents’ attic, I should not assume that it is from the current year. It may have just been moved to the attic yesterday, or it may have been decades before.

For a post about processors from the 70s, there is no default assumption of recency. This post is on Google Groups, which has existed since 2001, and which is a gateway server to Usenet groups that predate it. Absolutely nothing about it gives a shared context in which the absence of a year can be reasonably assumed to be the current year.