The Astros were below .500 for every season between 2009 and 2014, including 3 straight seasons for losing more than 100 games.
The Cubs were below .500 for every season between 2010 and 2014, including 3 straight seasons of 90 or more losses.
The Braves spent 4 seasons under .500, including 3 straight years of 90 or more losses.
The Phillies were below .500 for every season between 2013 and 2017, with at least 89 losses in all of them, but 90 or more losses for three straight years.
Your premise is wrong.