I mean Ukraine is already shooting down like 80% of rockets launched at them, it's just a matter of getting those percentages up while Russia goes through their limited stock of missiles.

As for Russian artillery, the solution has been implemented with HIMARS. Massive artillery barrages take massive amounts of ammo, and that requires good logistics and storing all that ammunition. You hit their ammo depots as Ukraine has been doing and all that artillery is dead in the water. And even if do avoid this fate, artillery barrels have a limited lifespan before they become useless and need to be replaced, which is another point of failure for a country with underwhelming logistics.