Weather computer models are capable of doing billions of mathematical calculations per second, whereas humans are capable of doing one calculation every few seconds. The amount of data the weather models are able to process makes them an indispensable part of contemporary weather forecasting.
It is true that weather models never get the weather exactly right, and sometimes get it very wrong. This is why the element of human experience is still a valuable part of forecasting.
The idea that computer models have made weather forecasting worse probably comes from a heightened expectation. Thirty years ago, people used to contact the weather office and ask if it might rain tomorrow. Now, people call and ask what time it will start raining and how much it will rain. Weather remains an extremely dynamic and complicated system, but it is becoming increasingly predictable, thanks to modern computers.