It is only limited by one's creativity and willingness to learn. If you can't make the game you want because the engine doesn't give you the option to, go ahead and learn coding. No, it is not easy, but it is not impossible, and no one ever said making games was easier. By learning how to code you can eventually bend the engine to your will, or straight up move to more robust engines.
Can't make art? Pay someone to make it for you, or learn it - I did, I literally learned how to draw in order to make the art for my game, so unless you are physically unable to draw, there are not a lot of excuses you can come up with. Can't make music? Once again, pay for it or learn how to make it. I am just one person with limited time, and I had and still have my fair share of learning with art and writing, so I have been slowly paying for two composers to make music for me.
Can't write? Read, write and practice. There are hundreds of resources on r/writing and on YouTube, and probably on sites such as Skillshare as well. With the willingness to learn, you will go places. Of course, another alternative is to partner up with other people. I prefer to work alone, so I took the time to improve my craft. It has been 4 years since I started my journey, and my project is - modesty be damned - freaking awesome.
So the only limitation really is the person using the engine.