Flamethrower can't crit/dh either, so if you crit/direct hit enough Scattergun it will jump above Flamethrower.
I guess now you'll do Reassemble + Chainsaw into Reassemble + Buzzsaw if possible, so no room for Reassemble + scattergun.

But the biggest problem is that Flamethrower remains a button to afk for 10 seconds.
Not pressing anything else for 10 seconds is simply against the nature of the game and just feels weird, unless you want to get a coffee.

I wish we could have Flamethrower to upgrade the 1 2 3 combo for a set number of GCDs.