Because the CCP under Mao liberated China from foreign oppression.

Now whether you might argue that it was thanks to or rather despite Mao being in leadership is another matter and believe me I am in the "despite" camp but it still makes sense that he would have strong symbolic importance for the Chinese people.

People that will argue "oh he killed millions of people" need to get their head out of the cold war propaganda. I do believe his economic policy was criminal and was done against the advice of Soviet advisors but it is still not murder. His policy was idiotic, he was neglectful maybe but he did not purposefully cause a famine.

Saying it is the same or even worse are the purposeful, planned industrial scale mass murder that Hitler was responsible for under the Nazi regime is pure holocaust apologia. Plain and simple.