Upgrading Ruby to 1.9.2 won't break your OS. Upgrading Python on some distros can even break package management. That's the difference.
And if you have a well tested, rock stable environment you generally don't want to mess with it if you don't have to, or may not easily be able to.
You want to not support older than Lenny. Well, we have machines that are still on Sarge, though slowly being upgraded. Some of the machines haven't been rebooted since around the time Etch came out and that's the main reason they haven't been upgraded yet.
That's only because package management "on some distros" (I won't name them, we all know which they are and I'm sure we're talking about the same one) is fubar. I'm not talking about the package manager alone, but also the over-the-top package dependencies, incoherent dependency resolver, let alone the sheer stubborness of some developers working on package management..
And if you have a well tested, rock stable environment you generally don't want to mess with it if you don't have to, or may not easily be able to.
You want to not support older than Lenny. Well, we have machines that are still on Sarge, though slowly being upgraded. Some of the machines haven't been rebooted since around the time Etch came out and that's the main reason they haven't been upgraded yet.