Interestingly, seat posts get stuck due to an electrolytic reaction between the aluminum seat post and the steel tube. Solution = grease heavily between metal parts even if they don't move.
I ignored the do no harm after a couple of bike shops refused to touch my stuck seat post. I used a hack saw and diagonally sliced off the post then cut two slots down the length of the post that was stuck in the frame. I then drilled through the post and inserted a screwdriver to crank/rotate the post loose. Yes, it was a real sweat but was rewarded with the post coming out.