Did you notice the examples were really old? Like late 1700s old?

Now, imagine you have a wooden box of lead or pewter letter forms. They're small, heavy and backwards. You spend your days lining up those forms in rows and then pressing them to ink and paper to print books and documents.

So you're lining them up, slowly running out of 'e's and 'f's and 'r's. You decide to save yourself some time and more importantly some of your precious few letters that you need to make last the whole page. So you omit some of those words, names in this case, and establish a convention with other printers and authors about how and when to replace words with shorthand. This lets you and your fellow printers save time by not having to work to arrange those admittedly duplicate letters and stretch those letters.

Fun fact, that's why old 's' are sometimes written with an 'f' missing the bar. Because they were re-using forms where otherwise a letter was so common they'd run out!