When initialising a variable with a composite literal, Go requires that each line of the composite literal end with a comma, even the last line of your declaration. This is the result of the semicolon rule.
Although possibly an unintended consequence, this means that when proposing a one line change, it really is a one line change.
The semicolon rule, by enforcing that each line of a composite literal is terminated by a comma, ensures that your one line change doesn’t include an edit to the previous line to add a comma.
It’s the little things that make the difference.