Is the condition of water flowing over every millimeter of skin in Wudu and Ghusl, especially given the difficulty of achieving it without rubbing or wiping, render the Wudu and Ghusl of the majority of people invalid, or is there a facilitation in this condition that the questioner has not realized?

Ghusl (ritual washing) is only achieved by the flow of water over the limb being washed, and this is a point of agreement among jurists. Flowing means pouring water so that it moves or shifts over the limb, not the continuous pouring and gushing of water. This distinguishes ghusl from wiping (masḥ), in which water is not poured. Therefore, if someone wipes their face with water without the water flowing, their ablution (wudu’) is invalid, because what is obligatory for the face and hands is ghusl, not masḥ, and ghusl is only distinguished from masḥ by the flowing of water.