But I'd be interested to know how your hand can supposedly resist collapsing- if it's neither made of steel nor creating movement in the opposite direction to collapse. Sure sounds to me like you're wasting effort by attempting to immobilise joints- like the overwhelming majority of pianists. That would explain why the tightened up joints actually helped you, where they ought to have limited you. If you're comfortable that your technique is a model of perfection that suffers neither collapse nor stiffness, then you're certainly a lot more cocksure than both this performing artist and myself. Personally, I find that openmindedness about the possibility that you haven't necessarily mastered everything goes a long way towards improvement...
I would never claim I have mastered everything or that "my technique is a model of perfection". It's simply stupid of you to assume something like that. On the contrary there's a lot I need to keep working on. But I have gone a long way to develope a technique that works for MY hands and at least two competent teachers who have actually seen me play seem to agree. Neither do I get tired or get pains from playing anymore. You have a really bad habit of reading what other people write in a way that helps you maintain your prejudices. When I said it's easy to use the palm muscles I did not mean it's easy to learn to do it (took quite a long time for me) but that it is physically not demanding after you've learned it.
Maybe a couple of photos would be helpful in explaining the issues I am dealing with (to various degrees depending on the individual finger):


The first image shows the normal finger shape on the right and hypermobile 1st finger joints on the left. The second picture shows hypermobility acting on the 2nd joints. The photos show what happens if I try to use straight fingers without being prepared. Do you or your concert pianist have such hands? Or have you worked with many students who have? Or maybe your expertice comes from studying such things?
There are special finger braces to prevent this type of over flexing. I've never tried those, but obviously the swelling acted in a similar way, preventing the unwanted flexibility while still allowing the fingers to curve normally.
Since the muscles in the hand only extend beyond the knuckle joints in the fingers, the ways to control the behavior of the other two finger joints are with the muscles in the forearm and by controlling the weight that is laid on each finger, can you agree?
My teacher and I are quite happy to call my worst fingers "weak". Yet there's no shortage of grip strength, I can carry a bag with any one finger. To think only about grip strength when discussing finger strength is a common mistake. The word not only refers to "the quality or state of being physically strong" but also to "the ability to resist being moved or broken by a force" (
www.merriam-webster.com). If the finger joints "break" from even the tiniest pressure, IMO that qualifies for lack of strength that is counterproductive for playing the piano.