Some financial systems, a large number of which run on mainframes, have databases where all fields are fixed length. (A database with fixed-length records is trivial to access randomly.)
One of my credit cards lists my name as "Christophe" rather than "Christopher" as they have a fixed-length 10 character field for first names. Customer support said it was unfixable.
It only takes one such system, in a complex web, to impose that limit on all systems.
