It's about energy delivered to the target. It would take a _lot_ of fuel to fire enough shots that are energetic enough to do real damage. Hundred of kilowatts or better.
That’s the reason the F35B may end up being such a game changer
Most of the breathless Popular Mechanix type articles gloss over just what it is that kills the target. Always trying to portray it as an instant kill death ray. "Dwell time" is never mentioned.
Trying to hold a laser long enough on a target that refuses to sit still is an issue.