Originally Posted by
Yaatri
Under certain conditions, reciprocal lounge use is a SkyTeam benefit. So is the earning of miles, although carriers have a lot of freedom to decide that certain fare classes will not accrue miles. I've never seen redemptions requiring more miles when a certain alliance partner is used, but a FF program could presumably block award tickets on certain partners without announcing it, like UA's reputed *net blocking. This isn't saying what would be good for DL's business, just pointing out some possibilities and precedents that could be chosen.
A list of SkyTeam alliance-wide mandated benefits can be found on the sky team website, although there always seem to be a lot of exceptions and fine print rules. For example, I expect SkyPriority to take a long time to be implemented by many SkyTeam partner airlines.