You clearly have some 4* or 5* heroes. That may have been written for someone far less far along in the game, or who is focused on which of the 3* they have to keep for use in events and tourneys.
Also, you are looking at these heroes from a titan perspective only, and you are forgetting that you can stun titans, as well as use mana potions to charge heroes up.
One could then argues that since they aren’t good at tians, all 3* heroes suck, since titans and 5* heroes kill them easily. However, 5* heroes are really, really awful at 4* and below events tourneys, for example, so do they then also suck? Given that, every hero sucks at something.
You have to compare like against like, so this is among 3* heroes. Here are the reasons:
Bane comes for free as your first decent hero, and has blind, and hits well.
Kailani & Gunnar actually help you stay alive by spreading out damage.
Beliuth & Hawkmoon heal.
Other heroes are good mostly due to fast speed, or dropping defense, etc…
Realize that at where you are in the game most 3* won’t work well for map farming, but some are still okay. Some of the Atlantis 3* heroes are much better.