It's not so important what you call it, coordination, strength, suppleness...always so much semantics in these discussions.
Sometimes exercises away from the piano are needed to achieve anything. It's not so much about lack of strength but all kinds of tension issues that people get from computer use and neglecting their body or training the wrong way for too long. Sometimes we are simply unable to even activate the correct muscles at all while others are totally stiff. If there are specific problems physiotherapy type exercises may be simply necessary in the first stage before the actual playing can be worked on. Even a good piano teacher cannot correct all the possible problems that are not caused by playing in the first place.
Some of these tools may help to relieve the overtension in forearm muscles and teach one to activate other muscles in the hand more. But of course only if used in the right way. While the fingers may not actually become stronger, they certainly feel that way when the playing becomes more effortless and the tone better. But if there are no actual problems with using the body parts then I see no need for special exercises either.
I also think it's a popular myth that everyone's got the tools for playing the piano as effortlessly if just taught in a certain way. Quite a lot of research exists about pianists' hand issues and they show that women, people with small reach and certain hand shapes are more prone to health issues. I see no evidence that one approach fits all. And one can play scales and other exercises or play on a heavy piano for months without any improvement...
From a student's point of you, if one is critical and finds out about things there's quite a lot of BS going around in teaching the piano. I guess it's because many teachers think that they can apply what worked for them to anyone and get the same results. Or simply teach without bothering to find out much about anything...