Why do you cling to false history that is so trivially easy to disprove? Wide sentence spacing exists from about 1530 to about 1950, and for the vast majority of that time, was so standard that I have never seen an english-printed text without it for most of that time period (and I’ve seen thousands of old texts). Note that typewriters weren’t available until 1873, and after their introduction, wide spacing continued in use for another 60 to 80 years.

There is no historical correlation between sentence spacing and the typewriter. Moreover there is no logical correlation. Monospaced fonts have absolutely enormous spaces, and it is completely irrational that you’d need more of them. The reality is you need less. This is also confirmed by the historical record. Wide sentence spacing that was in use when the typewriter was invented corresponded to roughly three word spaces between each sentence, and when the typewriter was initially used, most people use three spaces on the typewriter too, but it was too much so people reduced it to two spaces.

Finally, the wide spacing clears up situations where a period can be ambiguous or misleading in its usage. In other words, the spacing has semantic purpose, and is hence part of good grammar. (Even Charles Dickens agrees with me.) And in the modern era where computers are expected to interpret text, this is more useful than ever.