It takes a long time to design and a lot of material to make a big transformer and they last for decades. They are critical infrastructure so when one fails you want it replaced or repaired quickly but they are too expensive (millions of dollars/pounds/euros) to keep a spare unit idle for decades and the lead time for a new large power transformer might be six months or even longer. So repair makes sense, especially if it can be done on site because moving a big metal box full of oil, steel, and copper that weighs hundreds of tonnes is a major logistical exercise.
This isn't something that can be done by a company that 'moves fast and breaks things' and disappears next year.
There must be some extremely salty machinists that get bizarre part requests after breakage for some transformer from 1950. That could make a very cool YouTube video series: Following these machinists and repair people as their repair very old transformers.
But of course many such transformers are connected to equally old generators and they are a bit more challenging as far as making replacement parts is concerned, huge turbines for instance.