That advice was likely a holdover from the time when wedding rings were essentially insurance for the wife if her husband died suddenly - sell the ring and be able to live for a while on that money while you search for a new husband.

Now that women are, y’know, allowed to work for a living rather than being forced into homemakers, it makes a lot less sense for the wedding band to be outside of one’s means to purchase.

I just tell people to buy what looks nice to them and is in budget. My wife has a gold band with some inscribed decorations, and I have a band of silver and inlayed meteorite. They were both under $1000. No need for flawless diamonds, rare stones or precious metals. We’re happy.