I wonder how much of the facilities boom came from the economic growth of the 50s, and 60s. Every city I've lived in has a few facilities named "Centennial" that were built in 1967. They're still in use.
Meanwhile, the 25 year old cut-off used in the article kinda corresponds to the austerity of the 1990s. The facilities I've seen built since then (in Ottawa, at least) seem to be municipally required largesse from developers.