Not OP but in similar situation. Main reason is that the primary tables represent various official declarations, and they have a lot of fields. In addition, our customers are required by law to keep the data readily available for 5-10 years. Also the law states our customers are responsible for the data they send through our systems, so they want to see what they're sending.

So just to give an example of how field count "blows up", there can be up to 8 different parties related to a single declaration, and for each we want to have for display/print purposes our internal id, id in customers system, organization number, name, address, postal code, location, country code, contact person, contact person phone and email.

So we're talking about almost 100 fields just to store parties.

We want to store all that separate from say our "companies" table as a company might change name, location etc, and we're required to show/print the details from today 5+ years down the line.

We could put that in a separate table, but that means 8 joins to fetch data for a single record just there. And that's just one piece of the declarations, and at least 3-4 of these parties our customers want to see in overview grids and be able to filter on there.

Now tack on 20+ years of doing this, with various official systems coming and going with different technical requirements, and it adds up.