CPR is great for small club events where big money isn't involved, but we are nowhere near moving away from standard weigh-ins with the bigger events. Aside from the "gotta see it for it to be so" mentality, weigh-ins are increasingly about exposure for sponsors of the tournament and the anglers.
Tournament organizations like to boast about their live-release rates being at or near 100%. Granted, livewell systems are state of the art these days and anglers who take the time to properly care for their catch probably do no harm most of the time. But we will never truly answer the question of delayed mortality. As long as all fish were last seen alive, tournament organizers will claim 100% live release.