Well there are a number of other factors that come into play in a saturation attack. With anti-missile missile systems it doesn't really matter when the anti-ship missiles arrive on target. Eventually they will cause the target to expend all of its missiles. With a anti-missile laser, there is effectively unlimited ammo, so in order to defeat it with numbers you then need to add a layer of complexity to the attack, which then presents a vulnerability that can be exploited. The missiles would need to arrive at the target at the same time, or thereabouts. That's easy enough if you send a flight of aircraft up and have them fire together. But it's more difficult when you have, say, shore-launched missiles from different locations trying to coordinate with sea-launched missiles from ships at sea. Not a huge issue, but it could potentially come up.
Now, the advantage of the laser is that as long as you have enough power, you can keep adding lasers to your ship. Perhaps you can only build a laser to a certain power threshold, and that might necessitate keeping it on a target for several seconds in order to destroy it. But if you have 4 of them synced up, all hitting the exact same spot, you may only need a second to destroy it, maybe less. Imagine the number of lasers a nuclear-powered aircraft carrier could host. Not only that, but imagine the number of lasers a carrier GROUP could handle. This makes defeating them with numbers a much more difficult thing.
Well there are a number of other factors that come into play in a saturation attack. With anti-missile missile systems it doesn't really matter when the anti-ship missiles arrive on target. Eventually they will cause the target to expend all of its missiles. With a anti-missile laser, there is effectively unlimited ammo, so in order to defeat it with numbers you then need to add a layer of complexity to the attack, which then presents a vulnerability that can be exploited. The missiles would need to arrive at the target at the same time, or thereabouts. That's easy enough if you send a flight of aircraft up and have them fire together. But it's more difficult when you have, say, shore-launched missiles from different locations trying to coordinate with sea-launched missiles from ships at sea. Not a huge issue, but it could potentially come up.
Now, the advantage of the laser is that as long as you have enough power, you can keep adding lasers to your ship. Perhaps you can only build a laser to a certain power threshold, and that might necessitate keeping it on a target for several seconds in order to destroy it. But if you have 4 of them synced up, all hitting the exact same spot, you may only need a second to destroy it, maybe less. Imagine the number of lasers a nuclear-powered aircraft carrier could host. Not only that, but imagine the number of lasers a carrier GROUP could handle. This makes defeating them with numbers a much more difficult thing.