This was a fun read. There are a lot of repeated points seen elsewhere, but like you mentioned, I liked the economics perspective mentioned, especially in number 6. The more you can re-use and recycle from others, the better off your wallet will be. One does not (hopefully) have the economic efficiency of an assembly line alone, but can gain efficiency when teamed up with others.
I always sort of wonder about the point made in #4. It's easy to purchase a suitable item that is not designated for weddings because you simply hand over money for an item. The seller doesn't care why you're buying it if your money is good. But it's not really possible to do the same with services. I think an event planner will quickly figure out you are planning a wedding because, ya know, they're planning it. A DJ or caterer is going to show up and obviously see a wedding come the day of the reception. I've read multiple stories online about photographers not being told the event they were hired to shoot was a wedding in hopes of the couple saving money, and it leading to a lot of issues (not enough or incorrect equipment, no time to plan ahead for individual photos, missing "required" shots because they didn't bring a secondary photographer) and some angry feelings. I think you have to play this one by ear and be considerate of vendors if you use them.
EDIT: I'm dumb. I reread #4 and the author actually addresses this concern.
