The same really goes for Sector Artillery: not used a lot, easily dodged by leaving the sector (unlike Sturmovik attacks where you get one shotted even if you retreat right away). All in all not an ability with a lot of impact.
You underestimate the sector artillery. You can drop the smoke out of enemy LOS and it will still work on the entire sector. The only clue for the enemy will be the orange sector on the minimap, which is not something that you will see every in a split second every time. It's still rare to see this ability used though, despite it's power.
Other than that, there are indeed fewer OSWP options for the germans. That does not mean that there are no options at all. The most obvious one is the mighty Panzerwerfer. Even at max range this units has OSWP, at medium range it can one-shot multiple squads.
While the germans have less OSWP, they have options to quickly wipe squads when the opponent isn't paying full attention to the squad in question. For example, the rifle grenade, while not able to wipe full health squads, is a very powerful tool that can often lead to squad wipes in the later stages of the game where players can experience sensory overload. You can't see it coming on the minimap, you can't hear it coming either, and it can easily kill 4 models in cover. Combined with the firepower of the LMG42, it can quickly decimate a squad. I've killed many squads this way, and it's not something I can do as easily when I'm playing soviets.
Looking at the overall balance, while the squad wiping potential on paper is lower for the germans, I don't notice this in the actual game. While you would not expect it from a noob like me (remember our game the other day on Semoisky winter? You rude person!), I'm currently at rank 60 with both factions. From my experience in the actual game I don't have more difficulty wiping squads (or vehicles for that matter) with the germans than I do with the soviets.