Are canons against the spirit of philosophical practice?
In any case, canons are out there. This is evident for two reasons. First, every education program on philosophical practice uses a corpus of texts considered important for upcoming practitioners.
Second, every philosophical practitioner has a certain canon on his mind.
Is the word canon a matter of taste? Probably. Personally, I tend to think of canons in musical terms, where an initial melody is imitated at a specified time interval by one or more parts. To me, a canon demonstrates at best, the way philosophical practitioners communicate texts with clients and colleagues.
Neri Pollastri has compared the dialogue of philosophical practice with a jazz improvisation. To my opinion, this metaphor says more about the nature of philosophical dialogue than many treatises on the subject. Jazz is one possibility, but we could also consider chamber music, e. g. aduo or a quintet.
In the same sense, I think a canon is a good metaphor about how texts do not only circulate in the history of philosophy but also in the framework of philosophical practice.