I guess I naively thought the value of doing to others as you want them to do to you was generally accepted as positive.
Correct.
What about the teaching called the golden rule itself? Is it just garbage?
Yes, it's arrogant and presumptive.
Rather than assume people want the same thing you want, you could always ask them. For instance, just because person A likes for random strangers to stick a finger in his poop chute doesn't mean that he can assume everyone likes that and run around doing it.
Just because person B loves shrimp dinners doesn't mean he can assume every does, they may not like it or be allergic or have religious objections.
Far better to simply ask how people would like to be treated.