Agreed.
Tanking too often gets confused with rebuilding. To rebuild you first need to tear down the team and start building from scratch. It's a legitimate strategy in pro sports, shed bad contracts, put yourself in position to build around a new core of talent.
Tanking is not rebuilding... tanking involves intentionally throwing games... benching your best players on purpose so you lose. Did BUF bench their best players in 14-15? I don't think so. They put out the best roster they could... as did COL this year. Sometimes you just suck, doesn't mean you're intentionally throwing games.
Does fielding a team devoid of any real talent increase your chances of losing? Of course. But at no point did BUF (or COL) tell their players to go out there and lose on purpose. Why the NHL feels the need to punish those teams, I don't know.