There are a group of machines that can be "too old" because they are not actually old enough.
I'll take a 50-100 year old machine over a 25-30 year old machine any day.
The one thing going for the vast majority of sewing machines, they were never used all that much, some not even used enough to be properly broken in. It's rare that you find an old machine with serious signs of wear. but they can be worn out also. They don't normally "age" out like some plastic does, that will turn brittle even if it was never used.