I don’t know which people you are listening to, but Debian does not have newer packages than arch. It has older packages than almost all other distros. You can see this on distrowatch for yourself also.
The idea of Debian is that old = stable, which I don’t agree with personally. As an example, users of Debian are reporting tons of KDE Plasma bugs that was already fixed, but because they are running an ancient version, they still have the bugs.
But it depends. It’s correct that new versions of plasma had new bugs, that was fixed in the coming weeks or months.
I guess a better way of describing Debian is that it has old bugs instead of new ones, since it stays on older versions.