Good technique is about interdependence of all parts of the body; over-rely on one and it will fall apart or require endless hours to maintain. The vast majority of popular concert pianists have this kind of technique. Unfortunately, while this kind of technique is exciting to watch because of all the effort that is expended, it's a terrible way to play until your grave. Youth and vigor do not make up for age and arthritis.
About finger strength, yes it exists since fingers require muscles to move. However, in the context of piano playing, having large forearm muscles is actually a hindrance since it slows down movements due to the larger mass. Muscle stamina and endurance are a different matter, however. This is required since the muscles are being used very finely (fine motor coordination) and the muscles must be conditioned, both neurologically and energy-wise, to perform for a given length of time.
There are also other aspects of muscle conditioning that should be mentioned. The ability to hold a finger spread, e.g. holding an octave, requires significant training which does require the conditioning of muscles within the hand. If your hands are small, the karate chop muscle on the side of the hand, the abductor digit minima, must be trained to hold the open hand position. Otherwise, it will fatigue quickly. As well, training must be done to contract the muscle even more, i.e. increase reach/hand span.