In general, there are four rarities in MTG: common, uncommon, rare, and mythic rare
Sure, they can interact with it as it ticks up, but thats spending removal on something that isnt going to win you the game, which is bad for them
SWSH NAME :FA/PIKACHU VMAX Model Number : S8b 279/184 GRADE : PSA10 GEM MT SERIES : VMAX CLIMAX-ULTRA RARE
Even when a card is knocked into the graveyard, it still serves a purpose, helping to propel new cards to the fore thanks to the decks many delirium triggers, or it pops back into play thanks to its many reanimation effects
What else is there more to say
If your opponent doesn't have an enchantment or some other non-destructive effect to neutralize your newly-armored critter, then Mithril Coat makes your commander invincible