yes and no.
- yes panzwerfer/ katy have in a short time more firepower
- no, because they have long CD, meanwhile scotts can fire all the time
- no, because sometimes you miss your katya/ panzwerfer barrage
- no, because with the barrage from scotts you can stay out of at guns range
- no, because on some maps you can shoot with scotts over LoS shot blockers, so at guns can't hit you
True, but you're overstating the "fire all the time". It can't really fire all the time. It can do so in 1v1, perhaps, but in larger modes... I don't know of a single 3v3+ map that has LoS blockers over which the Scott can shoot with ground target. Well ok, mid VP big crates on Hamburger port for one side only (top side has the wall but that's super risky due the the big road that is easy pickings).
There is a much bigger impact of wiping 2-3 squads at once with a katy/werfer/stuka than taking model by model with a scott. Mainly, because the rest of the models will do damage to whatever is there. If I fire a katy barrage on 2 obers, they will retreat instantly or risk wipe or both.
If I micro with the scott to ground target over something, micro the units to engage obers at a favorable distance, only so that the scott misses or takes out a bit of hp of the obers, they will still do damage to my squads, bleed my MP by 80+ if they're at vet2 and lose maybe one or two models of the bunch.
Sure, the katy will go on CD, but I've possibly taken out 2 obers without losing any MP. And in teamgames, the CD on katy/werfer/stuka is useless. The volume of units on a non-proportionally bigger map means you need more time to plan the attack. So yeah, there is a CD, but in 99% of cases, the CD will be gone once the threat reappears.
Scotts being able to fire all the time is only possible if you're playing against complete mor***. Most of the time, scotts are used to barrage, preferably, smoke barrage (the best feature of Scotts).
2nd point. Sometimes katy/werfer misses. In 1v1 and sometimes in 2v2. 3v3 and 4v4, never. Unless you target a specific unit. That's something that is then easy to spot and dodge. Eg. you have 3 rifles advancing on your VP enemy and you hear the salvo. You won't retreat as some people expect it, you won't advance as some people deny that, you will side-step. Same with stuka and katy.
With the barrage from Scotts you can stay out of range. Yeah, sure, you can stay out of range. You can stay out of range with every indirect weapon, except vs 17pounder/pak43. This is not something special to Scott and as such provides no argument.
Again, last point. Some maps. I seldom play 2v2, and when I do so, it's unranked so I don't know, but on 3v3+ I don't know, except for the Burger King, of any map that has LoS over which the Scott can fire more than 2 shells without being in danger (that might or might not do any dmg)