I'm asking this using tonal in the sense it was described in a highly voted best answer I found with search on topic of tonal vs modal. I interpret what is said in it that tonality implies common practice syntax, generalized as tonic-pre-dominant-dominant-tonic by my understanding, whereas modality shares properties of tonality which include having a tonal center, and working with a scale with some kind of threshold for interval spacing, but differs by absence of diatonic function, the syntax, or voice leading conventions of the common practice period. In it rose the notion that there is music with an anchoring note that can be explicitly described as "non-tonal." It seems bizarre to me, but it was posted from someone with music education qualifications.
I'd have thought in general, the foundation of what tonality is, is to describe, before schemata coming into play, the treatment of a keynote as an axis that other notes revolve around, the axis implication presented musically through interweaving, bookending, or pedal point, and maybe other ways to perceptually urge a formation of axis, these things potentially being implicit themselves ex. mi-re-do--do--do-- melody repeating over chord changes as an implied pedal of sorts. — Did any of these forms of regularities occur in church modes and thus invalidate such a definition?
Having a tonal center or whatever other title to the same effect, a note that is important in a way the others are not, even if it is the only categorical split between notes, seems to necessitate a hierarchy of tension by definition. Is this where I've misunderstood? Is function not to be conflated with tension? Is function rather referring to part of a schema, as a stylistic convention in ways to apply and organize tension?
The I-V-vi-IV ostinato it seems to me, unless described as daisy-chaining phrases involving elided plagal cadence — which I would feel is contrived or unsatisfactory in a way — is not a fully realized syntax associated with tonality, whereas the passamezzo progressions arguably are. Does that mean it is modal? Does the answer change if dealing with ostinato of I-V-I-IV, or I-IV-I-V?
I apologize if any of the musing I supplied with the questions make the questions come off rhetorical or disingenuous. I really am looking to get to the bottom of this, and this looks like the right place to ask. The other message board on the net that's adequately populated is unfortunately plagued by some rather aggressive underachieving. I'll really appreciate if someone can clarify and expound on the matter, thanks!