Another asset they have (and monetize) is a vast library of old papers. For instance, if you want to read Kildall's 1973 classic "A unified approach to global program optimization" then ACM will gladly let you do so... after you pay them $15.00 for the 8 page paper. https://dl.acm.org/doi/10.1145/512927.512945
It's hard to see how this is compatible with their claim to be "Advancing Computing as a Science & Profession".