They take longer to recover from...
https://www.ergo-log.com/isolation-exerc ... -time.html
The more isolation exercises that strength athletes use in their workout, the longer their muscles need to recover. Sports scientists at the University of Brasilia published their findings in the Journal of Strength and Conditioning Research. Bodybuilders and fitness fanatics who like to do a full-body workout three times a week are better off doing as few isolation exercises as possible and as many multi-joint exercises as possible.