A city's main underlying function is to support its population's needs(and do so better than their other options, if it wants to keep them.)
It cannot do this optimally without sussing out these needs, keeping a dynamic awareness of them, and working to compare and implement options that best suit them (which will include balancing competing needs)
All the technological connectivity in the world will mean little if people aren't happy with it, if they regularly work against it or just choose to leave as a result of it.
Also,technology,as wonderful as it is at collecting things like emissions compositions & the like,is pretty dumb. There is no tech yet that is smart like a human & even when there is, it will never be able to understand the moment to moment vagaries of human action.Those can only be understood by the individuals participating.
So, harnessing crowd sourced intelligence intelligently is now and probably always will be a key part of making a city truly smart.