Why did critics from classicism and sentimentalism attack Ruslan and Lyudmila?

Critics from the established Russian literary schools of classicism and sentimentalism attacked Aleksandr Pushkin’s Ruslan and Lyudmila primarily because the poem flouted the accepted rules and genres of the day.12

By blending the style of narrative poems by Ludovico Ariosto and Voltaire with an old Russian setting and elements of Russian folklore, Pushkin challenged the rigid literary conventions favored by these schools. Despite the violent criticism, the work brought Pushkin significant fame, and the older poet Vasily Zhukovsky famously acknowledged the poem's success by presenting his portrait to Pushkin with the inscription, "To the victorious pupil from the defeated master."12