No Code can solve problems that have been solved so many times before that a bunch of developers decided there was money in solving the entire class of problems once and for all.
So I think they are great, because who wants to reinvent the wheel? It's so much nicer to pay someone else to deal with the problem while I focus on building solutions to novel problems.
Is it a paradigm shift? Yes, in the same way that Excel was a paradigm shift. When you make it easier to solve a class of problems, then people solve more problems in that domain.
Excel radically transformed so many industries because it suddenly became dirt cheap to do complex costs analysis, so instead of paying an accounting firm to run two or three various costs analysis for a product, they could instead be paid to find the optimal solution for a product to hit a specific price point. Suddenly, we have candy bars with 54.51g of chocolate in them.
Something to keep in mind, is when the cost to compete in a segment goes down, competition increases to the point where the cost to compete is driven back up. If anyone can build a competing product in a weekend with 0 background, then competing products are going to pop up where ever money is being made. And one of those competitors is going to innovate their way to the top, through technology, marketing, corruption, or some other means.