So very glad Gaga hasn't hopped onto the 1989 tour bandwagon

[Kayla 7,595]

I have a theory that Taylor doesn't invite celebrities that could top her on the stage. 

Think about it- the female guests she has had with her haven't exactly been performer-powerhouses or A-listers. 

So Gaga probably wouldn't be on her list even though she likes her. No use getting upstaged at your own show. 

EDIT: There's also the irony that she criticized Spotify for not paying artists enough but she asks these people to come on stage with her for free.