That's sort of a flawed perspective, especially now that shock damage is in. A large, high-damage laser can absolutely ruin a ship if it penetrates (and if we're talking about something with damage numbers approaching or in three digits, it will penetrate), where an equal amount of damage output by a number of smaller weapons would do much less effective damage. Medium-caliber weapons are good for dealing with lighter ships, FACs, and fighters because they're often able to penetrate, and because smaller ships have fewer rows of armor, increasing the likelihood of two shots striking the same point, but for dealing with large well-armored targets heavy lasers are king.
Here's an example:
Damage Output 71 Rate of Fire: 45 seconds Range Modifier: 8
Max Range 5,680,000 km Laser Size: 16 HS Laser HTK: 8
Power Requirement: 71 Power Recharge per 5 Secs: 8
Cost: 539 Crew: 48
Spinal Weapon Only
Materials Required: 107.8x Duranium 107.8x Boronide 323.4x Corundium
That's a 35cm Far X-Ray laser in an Advanced Spinal mount.
Damage Output 6 Rate of Fire: 5 seconds Range Modifier: 8
Max Range 480,000 km Laser Size: 4 HS Laser HTK: 2
Power Requirement: 6 Power Recharge per 5 Secs: 8
Cost: 156 Crew: 12
Materials Required: 31.2x Duranium 31.2x Boronide 93.6x Corundium
And there's a 15cm Far X-Ray laser. Now, let's be generous and assume that for whatever reason you aren't going to turret the 15cms. Four of them are the volume-equivalent of the spinal laser, but they only deal 33% of its alpha damage spread over four columns instead of focused into one. Now, granted, if the engagement lasts long enough for the 15cm battery to fire for the full duration of the spinal's recharge cycle, they'd do roughly three times as much total damage.
But that's not how it's going to function. Anything you hit with that spinal mount is going to be crippled or outright destroyed unless it's heavily shielded.
That's why I design my laser ships with a mixed arsenal, the heaviest spinal mount I can make paired with turrets carrying the largest lasers I can get a 5s cooldown on. The big laser can wipe priority targets out in the first volley (notably, I like to hold fire on it until I'm in effective range for the lighter lasers, rather than wasting a shot and having it recharging while within a better range), and the turrets can do PD work, split fire onto multiple smaller targets, or focus onto a second large target.
This works well against Swarm Queen shields as well, the laser laser blows off a big chunk of their strength while the smaller lasers keep it from recharging, maybe grinding it down a little too.
Basically, you don't always need a big honkin' gun, but when you do, you really need that high-penetration high-shock massive alpha shot. Gutting an enemy cap ship right off the bat means that all that time your smaller lasers are holing its armor is time where it's fighting with a bunch of destroyed systems instead of at full capacity.