This is a part of Oasis history that I never really looked into until recently.
I'm currently watching the Rock Im Park concert, and what strikes me as weird is that nobody stepped in on backing vocals. Why? Some songs just sound completely wrong without them. Surely between Gem, Andy and Matt, somebody could've sung harmonies. Or at least sing key Noel lines like "You and I are gonna live forever". Also, if nobody is going to sing Noel's parts, WHY INCLUDE ACQUIESCE AT ALL??!!??!! Surely they could've added in another song from the back catalog with Liam's vocals to replace that slot in the setlist. How about a crowd favorite like "Slide Away", or maybe something like "Some might say" or something from the under-represented Be Here Now.