They turned out to be expensive theater. One major problem is that company names aren't actually unique. An EV cert for "Stripe, Inc" still doesn't tell you that you're talking to the correct "Stripe, Inc". The other big problem was that users had no clue they were a thing, and when browsers tried to emphasize them in the UI it just confused users and made phishing easier.

You can still buy EV certs if you want to donate money to a CA, but that's about all they accomplish.