>>38193855They don't block trapping moves, just trapping abilities.
"Some reason" being that offense teams can only carry one dedicated answer to stall teams, so stall teams can carry one dedicated counter to stallbreakers (Dugtrio, for example), kill the stallbreaker, then basically force the opponent to forfeit or slowly get chipped out over 100 turns.
>>38193841Since it prevents the opposing Pokemon from switching out the next turns, hyper offense teams can use Fairy Lock when their Klefki is about to die then get a guaranteed good matchup the next turn.
