That work is still being done by someone in a data centre. But all these jobs went from in-house positions to the centres.

The difference is scale. When in-house, the person responsible for managing the glycol loop is also responsible for the other CRACs, possibly the power rails, and likely the fire suppression. In a giant provider, each one of those is its own team with dozens or hundreds of people that specialize in only their area. They can spend 100% on their one area of responsibilty instead of having to wear multiple hats. The small the company, the more hats people have to wear, and the worse to overall result is because of being spread to thin.