It's the increasing damage. If you hold a laser rifle with the escalating damage it gets high enough to disintegrate a heavy if you time it right, and that's if you heat the beam.

Now combine that with the OTHER five or so seconds of escalation and you can dump more damage per clip than a breach forge Potentially.

It's why when I cobbled up the scrambler lance bad idea it does a steady damage and doesn't share the escalation. It's a lot easier to hold a pinpoint laser on a tank than it is to hold it on a smaller dropsuit so the odds of applying 100% of that escalation approaches certainty. Especially from a rooftop perch where turrets cannot elevate and hit.

It's why I say that laser rifles are a bad idea as AV weapons.