Why aren't gaussian processes used more often?

I didn't learn GPs in school, rather I came across a Youtube video on it and found the concept interesting and dug deeper. I think I have a good intuition into GPs, and they seem incredibly good for modelling non linear data. I know they have disadvantages as fitting a GP is O(n\^3) and tunning the hyperparameters is almost an art, but still... why aren't they used more often? the assumptions we make on other regression models don't come into …

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