You haven't worked in a large company. :-) Much of the code behind your phone, the train system, chain restaurant ordering and any paper bill you get is likely 10+ years old. These companies undertake 5-year programs to replace ancient systems, and the 5-year programs frequently fail, and run late when they don't.
Yup, been through a couple of those. What tends to happen is the very senior engineers get architecture-itus and believe they'll actually be able to create this wonderful, flexible architecture that will withstand any future req change. Millions of dollars later, it's tossed in the trash and the old system is still selling, but customer retention is so high a focus at this point to stem the tide of exodus that all the developers do is put out fires now.
