>>97766660It's really not. There are tons of cards that just shut down Pendulum Summoning entirely (Anti-Spell Fragrance, Dimensional Barrier, using any sort of summon negation on the Pendulum Summon), and because most Pendulum decks are so reliant on having the scales set, they tend to be glass cannon decks with horrible recovery plays if you get rid of the scales and don't draw into new ones. If you lose both scales, you're really fucked.
You can destroy activated Pendulums with any sort of card that destroys Spells and the game is full of effects like that. You have to dedicate two cards in your hand to activating the scales, so going first, you'll almost always only have three monsters tops in hand, and you probably won't have that, so it's not a lot of board presence. Plus, the restrictions of Link Summoning under the game's newest ruleset cripple summoning the cards back from the Extra Deck because you can only summon to Linked zones or the Extra Monster Zone.
One of the best meta decks right now is a Pendulum deck, but it has nothing to do with the mechanic being strong, just the deck's absurd degree of consistency and flexibility on top of punishing your opponent for destroying your scales, making the downsides a lot less of an issue.