This site is underweighted on OLAP. Columnstores were invented for precisely this use case; nobody in the field wants to normalize everything.

Which brings me to the question, why a rowstore? Are Z-sets hard to manage otherwise?

Another aspect of wide tables is that they tend to have a lot of dependencies, ie different columns come from different aggregations, and the whole table gets held up if one of them is late. IVM seems like a good solution for that problem.