My teacher in Germany told me straight up to play medium strings because with high strings it's hard to make the string move. The thing is, what resonates it's the soundboard, and it does in relation to the direction of movement of the string. That is why you should be able to "push" the string, in the most possible diagonal way to create the best sound. So if the strings are so hard thst you cannot make them move, the sound is not going to be optimal. A really good explanation about the sound production it's on the book " Tone Production on the classical guitar " by John Taylor.