Why do Tanpura overtones not disturb?

Hi ALL, I have a query (though I have been singing to the Tanpura
accompaniement for the lasr 35 years!):

The Tanpura overtones, among others, include D, E, G and -Bb, when the
Tanpura is tuned as G3 C4 C4 C3. These overtones are quite loud and
easily audible.

Why is it that playing the Tanpura, thus tuned, does not disturb the
singer singing a raga which does NOT contain any of those in its
scale? Or, contais only one of those?

Thanks in anticipation, and regards,
Haresh.