As a Roblox programmer (Builder’s Club) scripting a game, the draw of addressing this huge user base by way of simply coding Lua scripts to release a product that invites In App Purchase is downright tempting! Then you discover the apparently wide spread client side hacking (speed, teleport, aim bots... you name it) and content theft (models, geometry, Localscripts) and pervasive scam attempts so frequently reported.…
I'm not sure what the question is, the two are hardly related. I guess you can use both to create games, but the thing is, you wouldn't have the network to go with it. I mean you could create a video but unless you upload it to youtube it might as well not exist. Or you could create a mobile game but unless it's in the app store (or featured / in the top x) it might as well not exist.
Roblox at least gives your content a chance of being discovered.