Why always the "Big 5"? There are also big clubs from the rest of Europe (Netherlands, Belgium, Portugal, Scotland, Russia, Romania, Serbia, Sweden, Turkey, Ukraine, etc.) that are BIG domestically and won BIG titles in Europe too! Some of them did beat the "big" Big 5 clubs in finals of the European Cup, Cup Winners Cup, and UEFA Super Cup. Clubs such as Aberdeen, Ajax, Anderlecht, Benfica, Celtic, Dínamo Kiev, Galatasaray, Gothenburg, Porto, Red Star Belgrade, Steaua Bucharest, etc. Some even won the Intercontinental Cup ... Yes, l would be welcoming of a less exclusive, more extensive and more accomodating quiz, to include other "forgotten forces" of the continental game (of a different age, before UEFA protectionism of the "Big 5", the Bosman affair, the elitism of access to commercialised TV football packages, profit-loving, non-football magnates' hostile takeovers of Europe's top clubs, progressively eroded and without remedy forever corrupted the parity of European football!
The last portugues team to win a major european trophy was Porto in 2010, 15 years ago! After that, only Olympiakos, a club outside from the "top 5", last year made it through the Conference League final and won. What you're saying belongs to the past, the scary Benfica, or the unstoppable Red Star Belgrade or Steaua Bucharest are all from the past (20th century). What do you think an american who doesn't love """soccer""" so much would know about those teams?