Because of the tendency to try preserving failed paradigms, giving rise to the use of nebulously applied concepts like “dynamic equilibrium.”
"Dynamic equilibrium" would be your term, not mine.
I merely tried to note that "equilibrium" can be a relative term, meaning a period of less apparent changes.
But "less" does not necessarily mean "zero", and can indeed include significant unnoticed modifications "below the surface".
And this is an issue for you, why?