1) 'Everybody's Free (To Feel Good)' was released in 1991. 'Rave' only started in 1987, so something that was released in 1991 is pretty old-school in my book.
2) The thread title is not 'favourite hardcore track'. It's 'favourite oldskool rave track', and as I previously explained, 'Everybody's Free (To Feel Good)' is old-school, and it most definitely was played at raves (Rozalla did live PAs at countless raves throughout the 90s).
3) The track was commercially successful, but that's only because it's so good!!!!