I've also run into this with an industry standard data model.
The PKs in this model are made up a concatenation of all the "natural" key data. So if you have a table of addresses with a natural key of Street, number, city, state , then the data might look like:
12333 East Southwest Promanade du Bicyclette No. 1243A
West Possum Crotch, XX
Then the PK would be giant varchar and look like this:
I'm not saying that this is a good natural key at all, but I can dang well tell you it is an awful PK. When West Possum Crotch consolidates with East Possum Crotch and becomes Grand Possum Crotch, all those rows will have to be updated.
But the guy who came up with this thinks it's a brilliant design and now it's part of a standard and hundreds of shops around the world are adopting it....