Debrincat is not a one dimensional player, he's a good passer and playmaker in addition to being a great goal scorer. Also never stated the addition of DBC alone makes them a playoff contender either, read my post again. I clearly said I dont expect them to be a playoff team in the next couple years, but if the rest of their young prospects continue their development properly then I could see them in the playoff hunt in 3-4 years.
You're also greatly underestimating the value that DBC brings to their team overall. Their biggest deficiency in the pipeline and current roster has been scoring, acquiring a young 25yo proven goal scorer just entering his prime that fits their age group addresses that issue and complements their overall talent pool nicely. It definitely helps their rebuild quite a bit without costing them any core pieces either, plus he's locked in on a team friendly deal to boot. Thats a great addition for them and will definitely help them become more competitive in the near future.