I have pet peeves, just like you. Want to know one of them? When people put two spaces after a period. It. drives. me. crazy. It’s one space after a period. Not two. That is the rule.
Want to know why? Back in the day, when we used to write on typewriters, typewriters used monospaced fonts. This meant that every character occupied an equal amount of horizontal space. Thus, we needed to put an extra space after a period to help distinguish the start of a new sentence. Unless you still write on a typewriter, which I presume you don’t, the extra space is just a waste of … eh, space.
When I got my first job in publishing at 944 Magazine the first thing my Editor said to me was, “Stephanie … enough with the two spaces. It’s one space after a period. Period.” Eliminating the space took a lot of getting used to, but now I’m golden. Just watch, now you are going to start noticing how many people still do it and it will drive you mad.
Pass this article on to them, it should help you win your argument.
Photo Source: This Etsy Shop