For normal matches, are you matchmade based on the number of stars in your deck? Is there any reason for me not to put plenty of 4 and 5 star cards in my deck? Or is it wiser to use stars efficiently so i will be matched with opponents who have similar amount of stars, which gives me a better advantage?
For starters, lower stars win ties. While this might not mean much to you, but cards like Sasha, Sandro, Lucy, and Melanie are beasts in the game (or at least in my opinion). That is not to mention that cards like Lothar, Platinum, Fanny, and Mona who are centered around this concept. Second, having a lower star count means you are more likely to go second (which is more helpful than you think... which is why it has its own Leader).
Now granted, few two/three star cards are perfect, but many of them counter your 4-5 stared cards, and win ties.
In normal matches (and for the most part standard format), the number of stars don't matter (at least, they don't in my limited experience). But on the upside, there is that great satisfaction of beating a player who plays 'unfair' (esp when their furious Carter is mauled by my 'weak' Lothar or Wesley).