I think freerolls can be useful in the following cases:
- To build initial bankroll at a site to avoid depositing
- To practice short-stack play
- To play while drinking
Even then, the low $added, many players typical for open freerolls are useless for BR creation.
The equity of freerolls is typically less than 50c, sometimes as low as 10c+. (equity is the $added devided by number of players). For example, a $100 freeroll with 500 players has equity of 20c per player. If this were not a freeroll, then one would have to pay 20c to get the same prizes.
Obviously, there is no significant money to be made at such low buy-ins regardless how good a player is.
Say that the win rate of a player is 2. (win_rate = $won/$equity). That's pretty good and means that for every $ invested, the player get's $2 in return. The $invested in a freeroll is the equity. That would mean that for the 20c equity tourney, the profit would be 20c. If the average amount of time to play is 2 hours, then that would be 10c per hour. A decent wage in China if you lived there.