First, it takes more than a second (and you have to remember to switch back). Second, you can't do a national search like you can with Kijiji.
So, for example, I was looking for an uncommon RV model and trying to search all of Canada, as I would have been willing to drive almost anywhere in the country if something was the right price. To do that, I have to change my location to St John's, search, change my location to Halifax, search, change my location to Quebec City, search, change my location to Montreal, Ottawa, Toronto, Thunder Bay, Winnipeg, Saskatoon, Calgary, Kamloops, Vancouver, Victoria, etc. With Kijiji, you select 'Canada' as your search area, job done.
Add that the search function itself is unreliable at best as noted above, and it's all way crappier than it needs to be...