Purely literary.
The triolet is one of many poetic forms that arose from the fertile, lyrical minds and hearts of Provencal poets in medieval France. Triolet continued a Provencal trend of repeating-line poems that eventually resulted in the villanelle rondeau. The earliest triolet writers were 13th century Provencal poets and French monks.
When the written rondeau soared to popularity in the 14th and 15th centuries, the triolet was relegated to obscurity. In the 17th century, Benedictine monk Patrick Carey actually tried to revive the form for his devotions, but he found no takers in a poetry community focused on lengthy verse. He was the first to write triolet in English.
The triolet was revived in the late 19th century by numerous British poets, led by Robert Bridges and including Thomas Hardy, who eschewed the form’s light, often romantic tradition and found it useful for punchy, serious verse.