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As I said, in randomly generated music there will be -passages- that have a tonal centre, and there certainly will be triads that also occur in traditionally tonal music. That doesn't make the piece as a whole tonal. You could build a whole piece out of major chords without having a tonal centre, if you don't connect them "logically". Debussy can't really be called atonal of course since in the background you can still sense forms of gravity towards the tonic most of the time, but his music goes in this direction, where chords, such as major seventh chords are no longer functional chords, but mixtures, like registration on an organ.
As I said, Schönberg and many after him avoided common "tonal triads", because a tonally trained audience is prone to hear almost -everything- as tonal (this is also displayed by the fact that we can hear chords in equal temperament as tonal and even "pure"), so they had to systematically avoid anything that would allow this. This -doesn't- mean a music that has chords built out of thirds is tonal. My question remains whether you'd personally classify, say, a highly aleatoric piece by Cage as tonal, where undoubtedly some of your listed chords will briefly appear.
Even Webern pieces -can- be regarded as consisting of intervals that create tonal centres. Just that the tonal centre changes with every second note.
Additional note: In traditionally tonal music, the tonic is never established with a single chord, but always with some sort of cadence. This doesn't apply to early music (say, pre-baroque) of course, which has other ways of establishing a clear tonality. And it doesn't apply to music of other cultures, where tonality is, for example, constituted by drones.
Further note: And all this is just regarding music written in a 12-tone chromatic system. If you used randomly generated -frequencies- the chance of actual tonal centres would diminish even more.
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