You're correct. The CFL isn't the NFL minor leagues. A lot of people consider it that, however, because the NFL does pick up a lot of players from there (and you're also right that many of them go back for the reasons you've stated.) It wasn't meant to offend, just that's what I was told & learned from research back when I was looking into options after HS.
Watch it calling the CFL "minor league." It is a different league with different rules and no affiliation with the NFL. The only difference is the pay scale, though there have been a bunch of CFLers who have gone to the NFL for the money and come back since they would rather play than sit on the practice roster.