This is true because you run Earthquake.
It's simple, Ground hits Rock, Steel, Poison and Fire and fire can all ready be hit by Rock Blast
Fighting hits Rock, Steel, Dark, Ice and Normal and Ice can also be hit woth Rock Blast.
Well, they're so similar in coverage, so which is better? That depends on how you look at it, simply. You might say that Close Combat is obviously a better choice because of the power it brings but the problem is Aegislash. Aegislash, that one single pokemon is the reason you run Earthquake. You might argue that it's worth it because Aegislash is so incredibly common, but you also have something we call a team. Your team can take care of Aegislash too. When determining which coverage is better, in all honesty CC is all around the better option, not the other way around.
But if you want both CC and EQ, you might actually want to consider ditching Pin Missle because, let's be honest, it's only used because it's STAB and doesn't have the begative effects of CC. Pin Missle provides very minimal coverage, hitting only Grass, Dark, and Psychic, when Fighting takes care of Dark anyways and both of Psychic and Grass are very uncommon and can be taken care of woth teammates, so if you're only using 3 attacks MHera and you really REALLY want to hit Aegislash you cab use CC and EQ, dropping Pin Missle for EQ.