I see where you’re coming from. In school we were also taught to NOT put a comma before ‘and’ if it’s a list. I also didn’t quite get it, and found it weird. However, if you consider ‘and’ and a comma serving the same purpose (linking the elements in a list), then putting a comma before ‘and’ would just make either of them redundant. I’m not saying I prefer either of the two, but at least there is a reason to it.
Oh, if anything, unless it’s in the last element, it’s easier to see paired items in the list ( ‘,’ -> next element; ’ and ’ -> still the same element, with ‘and’ inside). When it’s the last element, it’s indeed ambiguous. And then there’s /u/hakase 's comment:
“They went to Oregon with Betty, a maid, and a cook”, where Betty is the maid mentioned.
I see where you’re coming from. In school we were also taught to NOT put a comma before ‘and’ if it’s a list. I also didn’t quite get it, and found it weird. However, if you consider ‘and’ and a comma serving the same purpose (linking the elements in a list), then putting a comma before ‘and’ would just make either of them redundant. I’m not saying I prefer either of the two, but at least there is a reason to it.
The issue comes in when you consider there are times you’d want to group things. Example:
I would like a toolbox with 4 drawers: Nuts and bolts, screws, washers and chisels.
Oh, if anything, unless it’s in the last element, it’s easier to see paired items in the list ( ‘,’ -> next element; ’ and ’ -> still the same element, with ‘and’ inside). When it’s the last element, it’s indeed ambiguous. And then there’s /u/hakase 's comment: