Not true. The first nail in the coffin for Romantic music was Liszt's Bagatelle sans tonalité, written in the late 19th century shortly before Liszt's death. The piece was probably the first (by a prominent composer, at least) to stray from Romantic styles, which had matured and reached near-exhaustion by the time of Liszt's death. Schoenberg and his contemporaries accelerated the collapse of Romanticism in the beginning of the 20th century. A few Romantic/post-Romantic stragglers remained through the middle of the 20th century, but they were all unique cases by then.