I had similar thoughts, but how does one use an RDBMS without making use of FKs? Do they put all in one huuuge table, that has all the columns and is super sparse? Or some other fever dream of bad design?
And is even worse, this is stuff that I have seen in ERPs (I integrate with several).
One of them, not even use "date"/"decimal" types and all is mostly strings, there is not views or anything else, and the tables AND fields are called "F0001..".