What would burn in those manhattan buildings? Are the internal walls wood?
I don't know what would burn in the building I live in now. It's all cement construction. The internal walls are brick with gypsum over. The window coverings and furniture is flame resistant. I suppose I'd be screwed if my downstairs neighbor had a bunch of flammable stuff though. Also we have an underground parking lot full of cars... maybe I should invest in a ladder.
Wood is a great construction material. It has better insulation value than brick, and the CO2 costs are vastly better.
The most essential unspoken purchase for anyone living higher than the ground floor in an older building is an emergency escape ladder.
Your flame resistant furniture will pyrolize just fine once the apartment gets hot enough. Just takes one idiot keeping their budget lithium bike inside to ignite the whole mess--ask me how I know.
The construction is there to isolate suites and delay the spread, but don't kid yourself that a given suite doesn't contain enough fuel to have a major fire, given the right ignition source and tinder.
A old brick-wall building is basically a pretty shell protecting a wood frame.