There are different ways to think about complexity. In terms of the code that's being executed, certainly using a cross-platform framework is likely to result in more complex code as the final output. However, for apps that do not need to use a lot of native features, cross-platform frameworks can significantly reduce the amount of code that needs to be written.
It also means that the entire mobile team can become experts in one framework rather than needing iOS and Android folks. That said, it's certainly still helpful to have deep platform knowledge to debug/optimize in certain situations. But I think the point where using a cross-platform framework stops making sense is going to be very different for different applications.
There are different ways to think about complexity. In terms of the code that's being executed, certainly using a cross-platform framework is likely to result in more complex code as the final output. However, for apps that do not need to use a lot of native features, cross-platform frameworks can significantly reduce the amount of code that needs to be written.
It also means that the entire mobile team can become experts in one framework rather than needing iOS and Android folks. That said, it's certainly still helpful to have deep platform knowledge to debug/optimize in certain situations. But I think the point where using a cross-platform framework stops making sense is going to be very different for different applications.