This theory has been done to death so I may as well have a go too. To take someone's spot in first grade you should earn it by performances in reserve grade. How did the new young guys go in reserve grade? Oh that's right, there wasn't any! The development players were very hard hit by the effect of the pandemic.
Schu and Haumole were always going to be brought through this year, but to start with the incumbents sends two messages to the squad - loyalty to incumbents by giving them a chance to prove their worth, and young contenders know they have to earn a shot by performances, they won't just be gifted an opportunity 'just to see' whether they are up to it.
As it happens long term injuries to Siro, Davey Jetski Boyle Suli meant their were opportunities, well taken by Schu, Haumole, Harper & Sipley. None of which proves Des has no idea and was 'saved by injuries'. In my humble opinion!