Raspbian existed well before ARMv6 support dropped off. It's been their main distro from the outset, but mainstream distros with ARM builds only removed support for ARMv6 in the last 1-3 years (depending on distro).
Pretty sure Debian's armhf images have always required ARMv7 or at least for much longer than 3 years. There are also armel images but those don't use hardware floats which makes them much less performant than what the original Pi is capable of. Pretty sure that that mismatch is why raspian exists in the first place.