Oh, really?
IAH may offer more destinations than CLE, but for Canadians, CLE offers quicker flights (and easier connections at a smaller airport) to all U.S. destinations except maybe the Texas and near-Texas destinations. Canadians will have to backtrack (
way back!) to most U.S. destinations from IAH. "No way, eh?"
yes really. Maybe you could look at an AC route map. The bigger destinations are already covered by AC. AC gets more out of this partnership through international connections. Something Houston and New York/Newark have as international cities-and something Cleveland doesn't. It is both basic geography and marketing.
And for pure aerial geography your statement is also incorrect. Someone flying Calgary to Miami, for example, if connecting on CO, has a shorter flight via Houston. It is not just "Texas" and nearby areas; though those areas cover ~50 million people...
Ciao,
FH