Not quite. While it's true that they can buy every summer anew, they do not necessarily offload their underperforming players. Since Pep I can only think of Nolito and arguably Danilo. The others (Bravo, Mendy, Stones) were all kept around as cover and in the case of Stones came good (again) eventually.
If you want to extend this to Begiristain's tenure (summer of 2013 onwards), then there are a few more (Jovetić, Negredo, Bony), but others (Mangala, Fernando, Navas) stuck around for 3, 4 or even 5 years. For an 8-year period that doesn't seem too outrageous to me. The much bigger impact is with the £40-60m players such as Laporte, Walker or Bernardo dropping seamlessly to the bench/a mere rotation option. That's surely unprecedented.