Regardless of target lock or not, the way the game is set up, there will always be competition and there will always be a loser.Easy for a top tier clan like Avalon to say no target lock since you will always dish out the most damage to a boss.
Everybody will win sometimes, but the person who wins the most (either by strength in numbers or damage rng) will get stronger and further suppress the competition. Its really unfortunate this is the way things are but it is not easy to change, requiring an overhaul of game mechanics and changes in the way both the player base and the company functions. I don't think this is a problem that will ever be remedied.
Frankly, no target lock actually greatly decreases the RNG component of battles.
Taking into account damage fluctuation, whoever has the most favourable damage output in the time-to-lock will get the lock. When the competition is carried out through the whole course of the battle instead of just the TTL, the damage fluctuation is a more even representation of the winners strength and cannot be due to favourable fluctuation.
Although this more greatly favours the stronger group than the current RNG influenced system.