I think that poster probably meant feedback loops or virtuous cycles (ones that create beneficial second and third order effects, with outsized impact vs what you might assume based solely on the first order change), more so than network effects.
And so many tout increased density living as being the solution to homelessness and house pricing, the walkable city etc etc. But who wants to actually live there?
I live in an apartment. I'd rather live in a standalone house thanks. Then I might get to jump on these opportunities too.
Then, the obvious limits of social contract. Good ideas rarely get past the body of apartment owners. Getting them to agree on fundamental "the building is broken" bits is already like herding cats. Trying to get a "good idea" into play? Nah.
1. Hip pocket concerns, how do we pay for it? Cue shrill: "I'm not paying for it, I already pay too much for management anyway..."
2. Where is that big battery going to go? Cue shrill: "Not next to my apartment, I don't want to die in a lithium fire.."
3. How it is going to be wired in? Cue shrill: "That will make xyz part of the building ugly and reduce value of my apartment."
Some of the apartment owners don't live there, it is an investment, they won't pay for anything that makes living there nice. Some of the apartment owners live there but then care about stupid things far too much.("You can't chop that out of the garden!" "State regulations say it is a weed and literally should be removed on sight...")
This is why I want my own place. So that I can implement "good ideas"(obviously subjective) without others getting in the way AND take advantage of all the middle class standalone homeowner subsidies.