Or if not Algarve, then the Pan-Am games. Its the same year as the World Cup and usually pretty quickly afterwards, so the main team doesn't go anyway. When its during the summer, we could just send a collegiate national team and not even have to worry about taking players away from their teams.
And that exception is exactly what makes it a "not" a U23 tournament. It counts for nothing and has no pertinence to worldwide position or "real" soccer triumphs. That is, for the men, it is meaningless. If fact it almost meets one part of the definitions of pornography in that it has no redeeming social value.
The "tournament" encompasses the full scope of competitive matches played related to the finals of said tournament, which is why it's always constructed properly as the World Cup Finals/Olympic Finals/European Championship Finals/etc. (which take place in a country every 4 years). Qualification matches compose part of the tournament. So it IS a U23 tournament, with 3 exceptions provided for the finals of said tournament.