If a new face can reverse policy on a dime, then that reversal can be reversed a couple of years later.
It's amazing how few people seem to understand this. Countries are oil tankers, they take years to turn even a little - and that's a good thing. In 2000 the world broadly knew what was going to happen, Gore and BushII would implement pretty much the same policies. Same thing in 2008 when it was McCain and Obama.
Sure you get some minor tweaks to policies which don't really affect much in aggregate.
Even in 2016 Trump was unable to make massive changes, because the state is built to prevent that from happening. The US does not elect a monarch. Things take forever by design, and it's really frustrating when you want it, but it also means one person or one administration can't make a major impact, it takes a generation of pushing the overton window in the direction.
Once you break that, you have a jetski zipping around, then you can't rely on stability, it becomes riskier to invest than investing in a country with a dictator.