It was for a dynamically growing ring buffer that also did short-object optimization. The natural implementation was to have the capacity and the offsets stored in fixed locations and with a fixed width, and have the variable part be a union of pointer or inline byte buffer.

Depending on the element width, you'd have space for different amounts of data in the inline buffer. Sometimes 1, sometimes a few more. Specializing for a one-element inline buffer would be quite complex with limited gains.

In retrospect trying to use that as a running gag for the blog post did not work well without actually giving the full context, but the full context would have been a distraction.