Kaladesh had compounding factors, namely that energy was a complicated new mechanic with several costs having been misjudged, but had the designers been able to easily slap colored mana costs on most of the artifacts without tradition turning them away, things could have been different
The classic is Dark Depths and Thespian's Stage, but theres likely better options these days
Your opponent plays a big creature, you counter it
Even if you just tick it down to force some sacrifices and draw cards, thats killer on certain board states
Thanks to this, all the historic support works very well together, and even though all the Doctors have different designs and playstyles, they all mesh together for a solid Bant precon that's great out of the box
Lifegain is also technically a payoff but mostly it is an incidental one, it isn't a route to victory and shouldn't be the focus of a plan