How was I wrong in stating Serie A was considered the best league in the 90's? All you've done is chosen a different time period to prove a point that UCL wins matter. I only picked the 1990s as that was the most consecutive years Serie A was ranked 1st in the UEFA country coefficient. The best players in the world played in Serie A throughout the 1990s (R9, Maldini, Baresi, Batigol, Baggio, Zidane etc) and they were still very competitive in Europe. Juve reached 3 UCL finals in a row.
Well Uefa Coefficient had it ranked the best league in Europe for 8 consecutive years, due to the fact they were super competitive in all the major European Competitions despite not winning the UCL consistently. Between 1976-1981 the winner of the Ballon D'or was from a German club. They had the best players in the world playing in the league at the time. Keegan left Liverpool who had just won the EC, to play for a team that had barely won anything in Germany for decades. Yes it may not have hit the same level of stardom Serie A did but it was still a very strong league and best in Europe at the time.
My point is that winning isn't as important as you're making it out to be. Serie A in the period you described was a incredibly strong league, especially with the quality of players it had, which hasn't been rivalled since. Yet going off wins and the criteria you've used to assess league strength, they'd pale in comparison to La Liga of the 2010's. Does that mean Serie A in the mid 80s to 90s is inferior to La Liga of the 2010s? I don't think so unless you believe that wins are the be all and end all and as you said, who cares about quarter finals and semis? Or even number of runners up? Don't you think that's a bit dismissive? Only a sith deals in absolutes