They are quite good and typically better built (steel instead of plastic in lots of key places)

But they do not work as well out of the box. They require a lot more tuning and calibration. They also lack some quality of life features. For example, changing a nozzle on a bambu printer is a 15 second job. You just pop off the cover, hit the filament cutter, and the nozzle is magnetic. Changing it on a prusa core one is a few minutes and requires tools.

And on top of that, the prusa will cost considerably more and take longer to ship

They cost 3x as much