Yes, technically you are correct
if you consider the term "favourites" to refer solely to what bettors as a whole think. However I think it is perfectly acceptable to use the term favourites to solely refer to who you think is most likely to win. For any specific event there could be an number of "favourites" - e.g. a "bookies favourite" (who the bookies think will win), a "public favourite" (who the general public think will win), and "personal favourite" (who you personally think will win). I suppose it is my own fault for choosing a definition for favourite that included "especially by people betting on the outcome" - I probably should have stuck with the following definition: "favourite - a competitor thought likely to win"...
In any case this isn't really relevant. The main point is that stating that I don't think the Crusaders/Chiefs will win is not the same thing as stating the Crusaders/Chiefs have no chance of winning!
You are seriously suggesting that stating that "I think 'team x' are favourites" is different than stating "I think 'team x' will win"?
Instead of just stating "they are not the same", you will have to explain to my why they are not the same! Stating you think a team will win
does not mean you think the opposition has no chance

I'm sure every week you will say something like "
I think the Hurricanes will beat the Highlanders" - I'm sure you don't think that implies that the Highlanders have no chance....
There was nothing wrong with my original wording - the fact you (twice) thought that "I don't think the Crusaders/Chiefs will beat the Stormers" is the same as stating "I think the Crusaders/Chiefs have no chance against the Stormers" is really beyond my control
