Prior to PT San Diego, the EDH rules committee discussed Riftsweeper, and its place in EDH. Based on its agressive cost, substantial effect in EDH, and preemptive nature, the decision was made to alter the rules such that Riftsweeper's ability does NOT affect Generals in the RFG zone. This falls under Principle #1
listed here, namely that its power level:cost ratio is unacceptably higher in EDH than it is in other formats, due to EDH-specific rules.
Other Shuffle-into-library effects, such as Oblation/Condemn, still work as normal. The fact that they are reactive, and they allow the owner more opportunities to play their general and defend it, makes them acceptable to us.
As always, everyone is encouraged to play whatever house rules work best for your local community, but we believe that these are the rules which are best for the format at large, and will be played in the casual games after hours at PTs and GPs.
Gavin