The puritans were virtue-signallers par excellance, so that probably also flows through to what you see today.
That's the symbolism they are invoking when they kneel! They do not want to show a solidarity that they do not believe exists. That people would give up watching football over it sort of supports their side of the argument.
The short answer for why it is still played is "tradition". There's a lot of things in a lot societies that are "weird" for the same reason.
This seems a lot more fun to me than the current (awkward) practice of standing there trying to look more serious than the guy next to you, hand over heart, while some ostentatious diva who lost the last Eurovision contest belts out yet another over-dramatized and over-personalized performance.
The current incarnation of this tradition needs to die for aesthetic reasons, if not political ones.