One factor is the Arena format.
It favours short games as the more games you play, the higher you can rank in the Arena.
Berserk is aggravating this as rapid games becomes blitz, etc.
Swiss tournaments don't have the problem to favour fast play. But they are longer and is a larger commitment for all players so more than likely most teams go for Arenas.
Also few Lichess teams have actually committed players.
It favours short games as the more games you play, the higher you can rank in the Arena.
Berserk is aggravating this as rapid games becomes blitz, etc.
Swiss tournaments don't have the problem to favour fast play. But they are longer and is a larger commitment for all players so more than likely most teams go for Arenas.
Also few Lichess teams have actually committed players.