"Maker" refers to an entire tinkering movement. The projects are often electronics-related, but not always. And in any case, a "maker" generally isn't performing "engineering" in anything but the loosest sense (kind of like the criticism of most "software engineers" not performing "engineering").
> Would it be a proper use of language if a programmer called himself a "writer"?
No, because that would be confusing; no one uses "writer" in that way without extra explanation. In contrast, "maker" is used to describe a tinkerer who builds designs and/or builds projects, often reusing ideas from other makers. It's "proper use of language" not because it makes sense, but because that's how people use it.
> Would it be a proper use of language if a programmer called himself a "writer"?
No, because that would be confusing; no one uses "writer" in that way without extra explanation. In contrast, "maker" is used to describe a tinkerer who builds designs and/or builds projects, often reusing ideas from other makers. It's "proper use of language" not because it makes sense, but because that's how people use it.