Because the Slavonic letter names are ordinary words, the opening of the alphabet can be read as connected speech. Azu buky vedi glagol dobro yest gives, word for word, something close to I know letters; the word is a good thing, and readers have been finding sentences in the sequence for a long time. The reading is genuinely available in a way it is not for Greek or Hebrew, where the names carry no meaning in the language of the people using them.
Two cautions belong with it. The first is that no early text presents the names as a composed sentence. The reading is a tradition of interpretation, well attested in the modern period and popular in schoolbooks, rather than a statement about what the ninth century intended. The abecedarian poems, which are early, work the other way round: they take each letter as the first sound of a new line, which is exactly what an author would do if the names were not already a sentence.
The second is that the reading only works for the beginning. Push it past the first six or seven names and it becomes a matter of forcing, because the later names include Greek imports such as ksi and psi and the descriptive labels the Slavists gave to the yus letters. What the exercise really demonstrates is the deliberate character of the naming: someone chose short, common, teachable words, in an order that a beginner could hold in the head, and that choice is a piece of pedagogy rather than a hidden message.