Reactive maintenance isn't always wrong — for a genuinely low-criticality asset that's cheap to replace and doesn't stop anything downstream, planning around every possible failure costs more than just fixing it when it breaks. The problem is when it's the default strategy for everything, including the assets a facility can't run without.
The tell that a maintenance programme has drifted too reactive is a low Planned Maintenance Percentage: a team spending most of its week responding to breakdowns has no time left to get ahead of the next one, which keeps the cycle going.