Surely that's what lots of non-developer white collar workers use Excel for? I imagine there's orders of magnitude more people using Excel for data processing rather than Python or R. I'm well aware it's not the best tool for the job, but yet people are using it for purposes such as that. I wanted to learn more about that experience.
I think no. Most people don't do table joins very often. They wouldn't know how. What they'll do instead is create lookups with VLOOKUP or INDEX(MATCH()) to pull in values from other tables into their one master. And once they have the master flat file they'll use a pivot table for group by aggregations.