My minimum fire starting kit is a tiny ferrocerium rod with a length of about 1 1/2" and a diameter of about an 1/8". Even the luxurious version with a magnesium bar has enough place on a dollar coin. Pocket lint or paper handkerchiefs serve as tinder (or to blow the nose if required). It just does not take enough space to even consider leaving it behind. That´s also the case with a small BIC and a film canister of matches.
I wont take your challenge. A space blanket is part of the FAK and can double as shelter. It´s in my EDC even for urban environment. Those items just do not take enough space and effort to think about leaving them and not have them when you need them.
Preparedness is a lifestyle. When you live it, you have a different view on carrying emergency supplies. When asked to select "either a or b", the answer frequently is "both".