This card is easy to counter. If you press the surrender button fast enough your opponent won't get the bonus for fusion summon or for over 3000 damage.
it takes a lot of time to summon quintet. if everyone keeps preventing you from summoning him after it took you 15 min each time for graveyard preparation then you won't be getting a lot of cumulated score. You may as well play a weaker deck that goes faster to get more score per minute
All you need is Advanced Ritual Art + Keeper of Dragon Magic to summon quintet in turn 2. Nothing wrong with quintet. Magicalized Fusion is the one that should not exist.