To me a good canonical question has the following attributes:

• Addresses a commonly encountered question.
• The question itself is fairly clear.
• The answer is sufficiently concise to be readable, but detailed enough to be a complete answer.
• The answer is widely accepted to be the best answer for the question.
• Can be used as a Duplicate-Of target for close-votes

That last point is why so very few of our canonical questions are on meta.

That particular question, regarding *AMP installers, is primarily about category topicality which isn't a good fit for the canonical tag. If it's anything, it'd be a better fit for faq; the question is in a similar vein to this one about professionals.

To me a good canonical question has the following attributes:

• Addresses a commonly encountered question.
• The question itself is fairly clear.
• The answer is sufficiently concise to be readable, but detailed enough to be a complete answer.
• The answer is widely accepted to be the best answer for the question.
• Can be used as a Duplicate-Of target for close-votes

That last point is why so very few of our canonical questions are on meta.

That particular question, regarding *AMP installers, is primarily about category topicality which isn't a good fit for the canonical tag. If it's anything, it'd be a better fit for faq; the question is in a similar vein to this one about professionals.