I doubt anyone can actually calculate a line of best using ordinary least square linear regression by hand with no mistakes but no one’s crying about that.

That’s because I can write an algorithm to do it for me reliably and quickly.

LLMs are just the next generation of calculators and programs.

LLMs can do it quickly, but they cannot do it reliably by their very nature. They are very much NOT the next generation of calculators and programs, because the whole POINT of calculators and programs is to do it quickly AND RELIABLY.