I'm sorry if my intention wasn't clear enough!
You're absolutely right that right now, we are wealthy enough to be able to spend 4600$ on various "things" without either of us really batting an eye. That isn't really the important bit; when we first got started, I was making 42k USD in total comp, and she was making 26k in total comp. Our first house was 54,000 USD and our mortgage was 456$ per month.
We were not wealthy, but we were _okay_. And at that point in our lives, we still had a joint account as our only account. We didn't buy fun stuff or convenience stuff without a discussion first, and we had to discuss these things pretty much every week. That worked for us, because we still communicated, and the important thing - the thing most vital to my previous comment even working - is that we put our family first and ourselves second.
Now that my new home cost me 12 times what my previous cost me, and now that I'm bringing in about a quarter million USD a year, you're absolutely right that we are wealthy and the 4600$ isn't a major problem to us. But if for some reason it ever did happen - say, I lost my job and we relied only on my spouse's income, neither of us would be spending any money at all that wasn't absolutely required.
What I was trying to drive home with #4 is that if you and your spouse are always on the same page about what comes first; your personal desires - or your family's needs, goals, and then desires (in that order), then it works really well.
I know plenty of couples where one or more of the spouses is an incredibly selfish person by nature. Perhaps one of the other bullets in this article would accommodate that well enough, and I doubt #4 would even remotely work for them.
But for my family unit, a single joint account with both incomes going into it still works for us, even if we have very different spending habits between us - and it works for both of us really well. From our early days straight out of college making relatively low income until now where we make entirely too much, this way has worked solely since both of us are able to modulate and restrain our spending when times require it, especially since we put our family before ourselves. #4, as in the article, didn't allow for any wiggle room like that. That's okay, though, since it was hardly purporting to be an exhaustive listing and description of income:spending strategies! I just wanted to share that #4 can absolutely work even for couples without the same spending patterns, as long as they're willing to put family over self.