::: You cite the late Powers' article when he became arrogant and annoyed with too extended notion of modality. Check his NGD 1980 (widely disseminated) 90-pages article 'Mode' where he completely supported the common view of modality, and in his (large) article 'Tonal types and modal categories' and (another large) one about offertories, with pretty evident attempt to reconciliate 'modal categories' with his 'tonality' (especially see his batches of analytical tables). 
 ::: It was me who added the section 'Tonality outside common-practice period' in the current WP-page and, trust me, I invested much time in (fruitful) discussion in refining this section (see above on this Talk page). The 'tonality' in Powers' usage (applied to thed 16th century polyphonic sacred music) has nothing to do with the most common usage of tonality (= hierarchical pitch system with tonal center as reference pitch), he translated German 'Tonart' with 'tonality' which is the shortage of English language (Russian music theory uses  two different words for what an English scholar calls with one word 'tonality', but here is not a decent place to explain these complications). That's the secion is rightly located as marginal addition to the artice designed as an instance of 'encyclopedic genre'. But you don't hear me, so I don't think I should develop the evident things I outlined above once more.