That's just bad manners - publicly shaming the couple instead of fixing the situation as it's happening. If you allow children at your fancy restaurant, but they are disturbing other customers, it should be acceptable for waiters or hosts to ask parents, politely, to take their children outside (or into the bathroom in cold Chicago weather) until they calm down.
If your baby is crying or fussing loudly at a nice establishment, feel appropriately mortified and take him somewhere until he stops. It's on you to bring iPads, soft toys, etc, to entertain your child so that he doesn't disturb others. Yes, I know that children aren't supposed to look at screens at all until they're 2, but you're the one taking your kid to a $200-plus per-person dinner. Rules must be bent. Do not get all offended if restaurant staff or other patrons ask you (nicely!) to quiet down. Understand that your kid is being annoying, and take appropriate steps to shut it down.
If a baby is ruining your time, you can politely ask parents to keep the noise down. But also understand that sometimes parents of young children might not be being jerks on purpose; they may be so broken down and used to the hubbub that it doesn't occur to them that it's completely annoying everyone else.
For example, we were at a resort for Christmas vacation with my husband's extended family. We took our 1-year-old daughter to a casual, outdoor lunch spot next to a pool, and we gave her plastic stacking cups to play with so she wouldn't fuss. We're so inured to the annoying banging sound the cups make that we didn't realize that the sound would irritate other patrons. The table next to us kindly asked us to give our daughter a different toy, and we did immediately, and apologized. We felt terrible about bothering them in the first place.
Of course there will be jerks on all sides: nonparents who are nasty to parents, parents who think their little angels should be allowed to do whatever they want, restaurant owners who will take your money and then trash you on social media. But for the rest of us, just a little communication and understanding can go a long way.