[2020] "spawner spam is usually not a fun meta" -Seth, today

The answer is that X-Bow has a much wider range of counterplay than competitive spawner decks have had in the past. Spawners generate an outsized amount of Elixir for their cost (for example, Barb Hut makes 10 Barbs = 10 Elixir's worth) in exchange for the staggered deploy. If Spawners were all competitively viable then you could simply plop them down behind your King Tower and win about 50% of your games. Counterplay becomes limited to trading Spells, and that's not very exciting.

X-Bow however has a ton of counterplay because you must place it so close to the bridge. It's a constant tug-of-war at the bridge that some decks can handle but others can't. But that struggle over the X-Bow's spot is far more interesting and multi-faceted than high health buildings all the way behind the Towers.

The meta needs outlier / weirdo decks or else it devolves into beatdown vs. control grinds. Spicy decks like X-Bow, Mortar, LavaClone, or Freeze decks should not ever be 10% of the meta each. But if they total something like 10-20% of the meta between them, they provide interesting, unusual gameplay that adds a lot of depth to mastering any one deck.

If you are struggling with 2.9 X-Bow, might I suggest Earthquake?