Ideally, you want both.
Blender is good for making a fast rapid prototype to get the rough dimensions in. From my perspective, 20 minutes into prototyping in Solid or Fusion, and you’re spending most of your time trying to resolve conflicting constraints, or decide to scrap it and sketch from scratch. In Blender this is a non-issue, and the mesh modelling tools are amongst the best available.
When you got the initial thing in, and know the rough dimensions, drawing the thing in Solid/Fusion is a breeze. If you try to do that in Blender, it’s gonna fight you like a rabid werewolf. It lacks the proper tools for mechanical design, and you don’t have modules for lasercutting, sheet bending, milling, etc. There is a CAM plugin for Blender, and at least two CAD plugins, but they are pretty niche and limited compared to a full blown dedicated CAD tool.
Once you’re done, you bring that back into Blender for rendering, STL mesh cleanup, because CADs are notoriously bad at that, or minor dimension tweaks for early prototypes that you back-port into your cad drawings. Blender’s got a really good toolchain to make great renders of the models, really a question how far are you willing to go into texturing and material tweaking.
Rhino tries to merge those two processes to a certain degree, and afair Autodesk tried making a tool or a mode that did that as well. I think it was called Flow or something. Never found that useful personally.
I’m a Solid guy myself. Don’t like Fusion’s cloud features, though the interface is great.
Some people I know use Solvespace, it’s a common option if you want opensource or linux support.
Essentially, a mesh modeller and CAD software are complementary, and let you do things faster and more freely. It’s good to know both if you can afford the time investment.