VFX studios don't have a sufficient monopoly of talent - it's overwhelmingly piecework outsourced to multiple studios, and most jurisdictions give MASSIVE tax subsidises for VFX production (40-70% of total production cost).
The issue for a lot of productions is the budget per episode is low. For example, the show mentioned in the article has a budget of $15M to produce 6 episodes that heavily rely on shooting on location, significant set design, VFX, somewhat high profile actors, and a significant reduction in tax incentives by the Millei government at a moment when countries like Vietnam, India, Philippines, Colombia, and China are creating a second VFX production subsidy war.
Choosing to use GenAI to automate the creation of secondary scenes can become fairly cheap and is the lowest hanging fruit.