And why?!?! Just learn blender. Free, open source, the standard for Roblox developers. I don’t get why. If you don’t want to use blender, you’re going to end up with other paid software.
Yes of course you can. There’s one very obvious downside, you won’t be able to achieve the level of detail you would with Blender.
Bevels, smooth shading, and a whole buncha stuff I’m too lazy to list. Blender is more complicated but once you’ve got a grasp of it, it’ll be worth it.
Now this is not to bash on the Roblox modeling system, you could definitely still create a great game with great builds with the Roblox modeling system alone (you could make it better with plugins).
In conclusion, yes you can be a modeler without Blender but it does have many downsides to it.