There is byzantine and other late roman work of immense skill, just a strange spiritual perspective that deviates from the naturalistic/idealised synthesis the Romans built from the Greeks
I am no epic libtard, but I find it annoying when people place the decline of art on religion - art is an omnipresent expression and skilful art happens no matter the restrictions placed on it. Islamic geometric art mogs the shit out of any renaissance perspective work, egyptian and grecian urns with oblique/isometric perspective has more stylish and soulful simplification and linework than michaelangelo, some tribal pagan european metalwork mogs the fuck out of greek bronze statues or reliefs in terms of skill and intricacy, etc.
If you have an intelligent and spirited population, nothing can remove that inherent desire and skill will build up and be accumulated no matter how it is repressed or sublimated into other forms. Look how art institutions are universally poised against western art tradition, and so the same desire to build on the work of impressionism, academicism etc is sublimated onto coom art, commercial art, sublimely rendered YCH OCs etc. Its in the blood!