Why is astrometry uniquely suited for detecting planets orbiting at large distances from their host stars?

Space missions track stars over many years, favoring the slow evolution of long-period signals

Astrometry offers a distinct edge in finding planets residing at large orbital distances, corresponding to long orbital periods, such as analogs to the outer Solar System giants. Transit surveys struggle because a planet with a long period requires a massive commitment of time to produce multiple observable transits. Astrometry, particularly utilizing space platforms like Gaia that continuously scan and re-observe stars over many years, is perfectly suited to tracking the slow, steady, long-term positional wobble induced by these wide-orbit companions, which would be difficult to isolate using only short-term ground-based observations.