I agree - but it is arguable that a significant majority of poetry by canonical poets is settled in acclaim. Obscurities by them generally (but not always), are obscure for a reason.
This will not at all be the case with new and contemporary poetry for the simple reason that these things take time to settle.
Classic poetry has had enough exposure; contemporary needs support and nurturing. Some of it will fall by the wayside, some of it will become the canon of the future.
I should also mention that very many poets and remarkable works have due to matters of popular taste, etc has failed to secure a firm place in the cannon as it is now. So I think considering the cannon, older works and poets need continual relook and re-evaluation. Poets like Edward Young, Walter Scott, perhaps even Dryden, etc may fall into such a category. Even works of 20 century poets like Ezra Pound and Philip Larkin, aren't that popularly known to general readers.
I find the cannon limiting, for the reason that it does not cover enough of the past, it makes a narrow representative selection that misses out many unique and eccentric voices of their time.
This will not at all be the case with new and contemporary poetry for the simple reason that these things take time to settle.
Classic poetry has had enough exposure; contemporary needs support and nurturing. Some of it will fall by the wayside, some of it will become the canon of the future.
Let's help it get there.