Not sure what scripts you intended your comment about, but this is not true in general. If I type anything like किमपि (“kimapi”) and hit backspace, it turns into किमप (“kimapa”). That is, the following sequence of codepoints:

    ‎0915 DEVANAGARI LETTER KA
    ‎093F DEVANAGARI VOWEL SIGN I
    ‎092E DEVANAGARI LETTER MA
    ‎092A DEVANAGARI LETTER PA
    ‎093F DEVANAGARI VOWEL SIGN I

made of three grapheme clusters (containing 2, 1, and 2 codepoints respectively), turns after a single backspace into the following sequence:

    ‎0915 DEVANAGARI LETTER KA
    ‎093F DEVANAGARI VOWEL SIGN I
    ‎092E DEVANAGARI LETTER MA
    ‎092A DEVANAGARI LETTER PA

This is what I expect/find intuitive, too, as a user. Similarly अन्यच्च is made of 3 grapheme clusters but you hit backspace 7 times to delete it (though there I'd slightly have preferred अन्यच्च→अन्यच्→अन्य→अन्→अ instead of अन्यच्च→अन्यच्→अन्यच→अन्य→अन्→अन→अ that's seen, but one can live with this).