No sport is anywhere close to what is being proposed here. Almost every sport has various degrees of "half-assed" review systems, but they've led to massively more fair and accurate decision making than the time before them.
In addition with challenge systems there's the benefit of a perception of fairness. If you choose as a captain/batsman to use reviews and run out for spurious usage, you've got yourself largely to blame.
On the other hand, if it came down to umpire discretion exclusively, first of all the umpiring old guard inclination would go back to being hesitant in using it, and centralize the power back towards their own on-field decisions like the bad old days. Not even a malicious thing, it's just human nature. Additionally the players who currently have the agency would lose it, and for that reason alone would feel hard done by certain things not getting reviewed when they'd want them reviewed, even if these are once again spurious in the majority of cases.
So really the only choice you'd have is to always have a running review of the game being made in the upstairs video room, and while I would say it's possible for a video review tech / team to review every contentious ball in a timely manner without causing delay, the practical details of implementing such a plan in a way that's not completely alien to both players and umpires would be a massive challenge.
It's going to be a long time before we see a video review system anything like what is being suggested.
