Why is medieval plainchant sometimes incorrectly described as rhythmless?

Medieval plainchant is sometimes incorrectly described as "rhythmless" because it lacks the regular, metrically organized rhythm found in later Western music, which relies on recurring patterns of accented and unaccented beats. Because plainchant does not use a system of measure or meter, its notation is noncommittal regarding rhythm, leading some to mistakenly equate this lack of metrical structure with an absence of rhythm altogether.12

However, describing plainchant as rhythmless is considered careless terminology that denies the essence of music as a temporal art. In reality, plainchant is deeply rhythmic, though its rhythm is "free" rather than metrical. Its rhythmic character is determined by the natural accentuation of the Latin text and the dynamic quality of word grouping, making it "logogenic," or word-determined, music. While the authentic rhythmic style of early chant remains a matter of historical conjecture, it is fundamentally an art of "order in musical time," where rhythmic equanimity serves to symbolize an atmosphere of faith and inner peace.12