There's a difference between missing a payment and "carrying a balance" (making an on-time payments that are less than the full balance due).
I have heard mortgage brokers claim that, if you have no other credit history, carrying a small balance here and there on a credit card may improve your score. ("Small" is in relation to your available credit and your ability to pay it off.) But actually missing a payment will probably hurt your score.
You have a card with a credit limit of $1000. In July you charge $300 worth of stuff. You get the next statement and it shows the balance due of $300 and a minimum payment of $100.
If you pay the entire $300 balance in that cycle, most cards won't charge you any interest. You are not carrying a balance, so the credit scores may not reflect that you actually took a $300 loan and paid it off.
If you instead pay $200, you'll be in good standing (because $200 is greater than the minimum payment). But you'll be carrying a $100 balance into the next statement cycle. Plus interest will accrue on that $100. If you do this regularly, your credit score will probably take into account that you've taken a small loan and made the payments. For those with no other credit history, this may be an appropriate way to increase your credit score. (But you're paying interest, so it's not free.) And if the average balance you carry is considered high relative to your ability to pay or to the total credit available to you, then this could adversely affect your score (or, at least, the amount of credit another provider is willing to extend to you).
If you instead actually miss a payment, or make a payment that's less than the minimum payment, that will almost certainly hurt your credit score. It will also incur penalties as well as interest. You want to avoid that whenever possible.
My guess is that, in the game of telephone from the banker to you, the "carrying a balance" was misinterpreted as "missing a payment."