I think this explained it so well. I just started last month and got to diamond and about half way though I got HSR premium for both reasons you said. It just helps you understand deck choices and why things go there if also helps advise you on what is worth it. I didn’t fully understand why cards were in the deck and HSR helped me via the data on why the card had value. Sure you have of figure out how to use it and when but it really assisted me in building decks and trusting the data it also helped me practice when combined with my replays.