In the interest of accuracy, arrow's don't paradox, they flex. That flex may be sideways (fishtailing) or up and down (purposing).
According to my Webster's dictionary, paradox is a statement (or observation) that is seemingly contradictory or opposed to common sense and yet is perhaps true. When the term was first used/applied in archery, it was used to describe the orientation of a nocked arrow on selfbows, which had no arrow shelves or very small arrow shelves.
Thus, when the arrow was nocked and in shooting position, it pointed to the side of the target. It appeared that the arrow would shoot way to one side of the target, yet when shot, it hit the target. How could that be? That was the paradox, the archer's paradox.
We know now (through high speed photography) that the arrow hits the target where aimed because it flexes around the riser. And the reason it flexes around the riser is proper spine or stiffness. Of course, with a bow cut past center, the arrow can be lined up on the string and there is no archer's paradox.
A release gives a cleaner release than fingers, which roll the string to the left at release for a right handed shooter. A mechanical release greatly reduces or eliminates this roll.
If you have a bow cut past center, and the arrow lined up on/bisected by the string, there is no archer's paradox, as noted above, and, because the mechanical release imparts little or no sideways motion to the string, arrow flight should be excellent. The cut past center feature also enables the use of a much higher spined arrow than the bow's weight.
It isn't absolutely necessary to shoot a bow cut past center with a mechanical release though. A mechanical release will also work with bows cut to and proud of center, but arrow spine/tuning becomes more critical.
If your arrows porpoise when using a release, the problem can most likely be corrected by changing the nock height.
A friend of mine went to a release not so much to deal with arthritis or other finger ailments, but to deal with target panic. It worked for him.
Good luck.