I made it to 35th last week (this this event previous weeks) faction event, and didnt farm level 20. Its entirely doable to get on the leaderboard.
It is a great design for people who dont want to spend 30 min per clear. And dont forget all the low levels, who cannot play in higher delve levels.
Everyone should decide for himself if he want to hit higher or not. After all there is a punishment for not clearing the boss room. I really cannot undertand that this is a problem for some people…
This could have been done by making lower levels available to play and slightly changing the way rewards are determined around that. Instead now players have to use a semi-exploitive tactic in nature by deliberately defaulting when they would easily beat the level.
If I may (from the Gems of War Support article on Faction Events, https://gemsofwar.zendesk.com/hc/en-us/articles/360000360056-Faction-Events):
Not only are the devs aware, they are advertising is as a potential strategy. The article (part of the new Game Guide section of Support) also contains lots of other handy-dandy, useful information, so go check it out!
This is now true