[38]

Or better yet just year 0, why not? Do we say the 80s start in 1981?

[rdlw]

The concept of zero was not popularized in 500s Europe, when the system was devised.

[karatinversion]

And also, the system is a direct descendant of regnal numbering, where zero wouldn’t have made sense even if invented (there is no zeroth year of Joe Biden’s term of office).