Never had a problem with it on Windows. But like I said, nn Kubuntu for example, if you uncheck it (which you have to somehow know that you need to open the console and execute alsamixer and uncheck it), Kmix (by default) will just recheck it for you, which sucks. You can change Kmix though, but it's a bad default.
Just to say something..
If you install the Realtek HD drivers, you're STUCK with their crummy configuration interface.
finding the "mic boost" option is in the weirdest spot ever,
windows' built-in sound config doesn't work anymore for recording (sliders are disabled),
It's things like this that make arguments like yours useless.
you're complaining about 3rd party software, which just happens to ship with ubuntu, just like it would if you bought a store computer with the drivers pre-installed.
atleast in ubuntu you get the choise to kick that software out and replace it with something that DOES work right.