And for that reason they are not entitled to an opinion?
I think the point might be whether an ignorant, ill-formed opinion is equivalent to one made with a greater understanding of reality.
While many smaller, low-key races (usually 10km and under) are held in various parks, there is no way logistically to hold any race of any decent size (let alone big ones like Sporting Life 10km or either of the two marathons) solely in parks.
People think High Park for example, is pretty big. Harry's Spring Run-off 8km is held there in April, but they have to cap participation at a shade over 2000. Even then there is simply not enough park road space for any longer distance (there is overlap with the leaders finishing their last km while slower runners head the opposite direction towards the 3km mark).
The Waterfront Marathon last September had almost 3000 starters while it's accompanying half-marathon had almost 8000 (they share the same start time and first 17km of the course).
Even the 5km, held on a different course had over 4000 participants and there was still a steady stream of people crossing the start line when the leaders were in their final km.
Simply put, there is no possible way any of these events could be possible without exclusive use of two to four lane roads their entire distance. That just does not exist in the park system.
There's a reason they also don't hold the Santa Claus parade in the Don Valley or why the Maple Leafs don't play out of St Michael's Arena and that's because there are simply too many people to hold it anywhere other than where they currently do.