Is mastering really needed?
The majority of tracks need mastering in some degree, Sometimes they only need a little like basic leveling and some minor EQ details. Others need extreme eq and compression and anything in-between.
Most of the commercial released music is mastered. So if a track isn’t mastered, you will have the risk your track does not stand out against other tracks when played in clubs, Youtube, Soundcloud, I-Tunes, mp3 players or on the radio.