Why were full stops used in old texts after singular words or incomplete sentences?

This is a table of 17th-century mathematical notation standards by Samuel Jeake. It looks completely alien, compared to our modern notation, but that’s not relevant. What is important to note, however, is how every piece of text on the table ends with a full stop, regardless of the grammatical context. From what I know, the convention is to use a full stop to end a piece of text if and only if there is a complete sentence.

Spraying full stops to end even singular words seems to be a common trope in older written English. This example is from 1671, but newspapers in the 20th-century have done it too. Why was this done, and what is the historical context thereof?