Very often yes, to a scary degree. The amount of data normalization, adjustments, aggregation, analysis, etc that happens in some poorly documented and ill maintained macro is mind-boggling (there is a term for it - a model/process being "offline", i.e. not properly source-controlled or auditable).

The real reason is because Excel is still by far the simplest, quickest way to get something done fast when the deadlines are always "yesterday!".