Okay, so Roblox is a big corporation that makes a lot of questionable decisions. It's also indubitably a game platform for children, no matter how much they try to stray away from that image, but what people tend to miss about Roblox isn't anything about its gameplay. It's actually about the development cycle, or rather how easy it actually is to develop for it.
Let's first take a look at the Roblox avatar.
Depending on which avatar setting you have, it'll either have six bones or fifteen bones. It's also completely customizable on the website, isolated from any game. You'll see that my avatar consists of basic colors and a few user-created accessories, but you can also make it look like basically anything, so long as the items exist.
This character system is the first of many conveniences that Roblox provides developers: they don't need to make characters of their own (and if they do, they can just take catalog items).
Let's also focus on how easy this makes animating. Roblox avatars aren't just simple (it's really easy to animate using them), they're standardized. Animations don't just work across characters, they're literally given to you by Roblox themselves. If you don't want to animate, you don't have to.
Now going into Roblox Studio, you'll notice a toolbox full of assets by other developers.
This is the another convenience that Roblox gives you (though other engines do also give you pre-made development assets). It's very easy to transfer builds, scripts, and what-have-you from developer to developer, and there's a place on the DevForums where you can just share what you've made for public use. There's a lot of development kits lying around that you can just drop in so that you can focus on the concept you want to build instead of trying to figure out how to even make the framework for the smaller necessities.
And then there's the feature that makes Roblox powerful. It's not something you'll normally notice even: this feature is the fact that Roblox hosts your multiplayer servers for free. It's actually the entire point of the platform in the first place!
If you want to make a rudimentary multiplayer game, you can just hash out the concept, put a few days into building and scripting, and then let Roblox deal with the work of hosting the server for you! Plus, you have the Roblox algorithm alongside whatever advertising you're already doing.
This is all to say that Roblox as a development platform is incredibly easy to work with. While it does have a reputation for being geared towards a younger audience, it shouldn't be brushed off as being simple and incapable just because of that. Roblox is a game engine with incredible potential waiting to be harnessed by the savvy developer.