How seriously should I take size and weight limits of hand luggage? covers every airline and all the time in the world. The number of answers also indicates there is something wrong with it IMO. I voted to close it as too broad but noone else did so maybe I am misunderstanding what is too broad.
While I agree it is broad in scope, the question is essentially asking for a generic explanation of how airlines approach hand luggage size restrictions. These restrictions may change day to day between different airlines, but they all follow certain patterns which frequent travellers know about. There are other relatively broad air-travel questions that were well accepted on this site:
When you read the title, the question seems to be too broad. But in the body it's narrowed down by adding an airline and even a destination.
On the other hand - all answers are generic and only the top voted one has some information about WestJet.
In my opinion - the question is not too broad but the answers are. But we cannot close the question because of that.
The title is just a summary. You need to read the question, too. It is then clear that the question is about WestJet. Instead of voting to close, you should have just edited that one word into the title to make it a better summary.