Drop feeding is useless for lots of players.
But for some player's, it's useful to hit the ball with solid kinetics, like the first ball against a wall, so you get in practice to hit real balls, not slap shot first ball feeds in rallies.
Most of us play like we practice. Notice lots of guys on here feed the first ball with a side/underhand slap, and hit their forehands like that.
Not every player needs to concentrate on the first feed ball, but some do.