the general problem with any technique that isnt just throw some vaugely green thing behind our actors is that setting up complicated tech like this on an actual film set is extremely expensive. both the time it would take and the risk of it not working. so you end up with a dedicated permanent stage install but now you need to get the actors and crew to that place. better keys isnt a bad enough problem to justify that effort/cost. even the highly touted "virtual production" mandalorian stuff where you just put a big led wall behind the actors has shown to be more expensive than traditional vfx unless you tightly control the creative or approach.