I live in outer Paris (19th) and have the exact same experience. I’ve taken strollers on the subway without an issue and people are eager to help you (it should be easier, of course, but it’s doable). I've also taken the bus, the tramway, the RER. These days I’ll carry my son (almost 2) or take a baby carrier to go faster on the subway.

Bus are slow because of cars.

I’ve never seen a drug addict on the subway (you do see homeless people though certainly).