If you want to rely on missiles for armor breaking you absolutely can.
Yes... for flagship, and if the enemy is vulnerable. AI will dump most missiles, especially the likes of Swarmers and Annihilators. (AI likes to hoard Reapers too much, though.) That hurts if I swap ships for whatever reason. Even so, perfect use of missiles is not easy as others said, given how missiles work.
Heavy Mauler does not have perfect accuracy like HVD. Its low DPS would be more tolerable with perfect accuracy, but sadly, it lacks HVD's perfect accuracy. Combined with slow fire rate, it makes it mildly difficult to snipe at a pack of swift attackers.
Hellbore is a heavy weapon, which Enforcer and sub-capital midline ships cannot use. For ships with heavy mounts, I do use Hellbore/HAG/Mjolnir for anti-armor and anti-hull (except Onslaught, in which case, TPCs are used instead to get the job done.) The ships where I would like a more elite medium HE weapon do not have heavy mounts, and the ones I would use (the midline ships) have few small missile mounts, and getting Expanded Missile Racks would eat too much OP for them.
So you’re out here saying “missiles are bad because I can only destroy half a lategame fleet with them before having to rely on the other 30 ships in my fleet” and I am astonished.
Which is why I prefer simple guns if available. Heavy Mortar pairs nicely with Railgun, Arbalest, and Storm Needler; and Mauler pairs nicely with HVD. (Mauler and HVD combo is not good against an advancing beef wall that laughs at low DPS.) Heavy AC/Needler pairs decently with 900 range heavies, but not all ships with medium mounts have heavy mounts. 800 range kinetics does not always pair well with 1000 range Mauler, depending on ship and AI (not to mention Mauler's low DPS despite being a high-end medium). 800 range kinetics pair better with Heavy Mortar, but reduces range band (to 700) if I want to pressure enemy with all guns, which wastes the kinetics' extra range.
I do not want to use rely on my entire fleet, just what I can deploy on once. If I need to retreat-and-deploy reinforcements, then I should edge-camp to minimize time to retreat. Especially if my fleet is weaker for some reason and I do need most of my fleet for multi-round combat.