The person maintaining an outdated system may understand its limitations better than the person defending it.

The person defending a system usually knows it from the outside, as a story about what it does. The person keeping it running knows every place it fails, every manual patch, every category it cannot represent. Their knowledge is more accurate and carries less authority, because being close to the machinery is treated as a technical matter rather than a strategic one.

Before any decision about a system, ask the people who operate it daily what breaks and what they work around. Ask specifically rather than generally, because they have long since stopped volunteering it. That conversation is usually the cheapest useful hour available.