No need to accept mold in your house.
A huge part of cities (I’d argue the biggest part) is cleanliness and hygiene. Cities need to consolidate and remove their waste to avoid illness and outbreaks. There is also an economy of scale, a municipal composting station can break down more things, and more quickly, than everyone doing it at home (not that they can’t or shouldn’t if they want to).
The best way to keep decomposers out of your house is to move the things they want to decompose OUT of your house. This is way to much for an individual to manage in tight quarters, so we fall back on a city’s economy of scale.
Basically, a city needs a systematic approach to decomposition, it’s impractical and unhygienic to be doing so on a small scale within a city (the rules are certain different for something more rural or homestead-y)
Sure, but dead plant parts should be outside your house when decomposing. Same with food waste. Economy of scale still exists with municipal composting.