What I do see is "classism is the biggest humanitarian crisis of our age," and "solving the class problem will improve people's lives," but no where do I see that non-class problem will cease to exist. People will still fight, get upset, struggle, just not on class terms.
Maybe you read a different set of Marx's writing. Share your reading list if possible.
That said my comment was looking mainly at the result of Marxist ideology in practice. In practice millions of lives were lost in an attempt to create an idealized world. Here is a good paper on Stalin’s utopian ideal [2].
[1] https://www.jstor.org/stable/10.7312/chro17958.7?searchText=...