Why did the poems in 1950s and 1960s have a realistic narrative tendency?

In the poetry of 1950s and 1960s, the tendency of "realism" was manifested in the abnormal "prosperity" of narrative poems, and on the other hand, most lyric short poems had the framework of characters, scenes and events. The "upsurge" of narrative poetry creation appeared in the "liberated areas" in the 1940s, and it was continued and developed in the 1950s and 1960s. According to rough statistics, there are nearly a hundred long narrative poems published in this period. For example, Chrysanthemum Stone, Song of Life, Biography of Levin (***3), Xiangkunlun, Ruan's Golden Conch and Symphonic Poems of Baiyun Obo, Three Long Battlefield Poems, Warsong of Heroes and Biography of Driving (***7. Guo Xiaochuan's Ode to Snow, Deep Valley, One and Eight, Severe Love, General Trilogy, Ai Qing's Black Eel, Hidden Gun, Wen Jie's Revenge Flame, Dongfeng Urging Huang Helang, Qiao Lin's Malanhua and Wang Zhiyuan's Walnut Slope. Although the ideological and artistic value of these nearly 100 long narrative poems cannot be generalized, some critics questioned this situation in those years, but they regarded the style of poetry as the "task" of novels and dramas, and did not consider artistic methods from the morphological characteristics of various literary styles. Comparatively speaking, the narrative poems created on the basis of sorting out minority folk poems have a high artistic level. Among them are Xu Jiarui, Gong Liu, Xu Chi and Lu Ning's long poems of the same name, Bai Hua's Peacock and Wei Qilin's Hundred Birds' Clothing. Gao Ping's narrative poems "Lilac" and "Snow" written in the mid-1950s are based on Tibetan folklore and folk poems, and also show the height of narrative poetry creation.