The big downside is when you park you don't just need to know the conditions when you park, you need to know the conditions for the entire length of your intended stay. You also need confidence that the signs will remain unchanging throughout your stay because if the signs update and you get a ticket the burden of proof is going to fall on you to prove your innocence.
This concern is only relevant if you think that the only thing preventing the regulators from changing the signs is the technological hassle of doing it. If you rather believe than the signs change based on the need to accommodate a film crew for a few days like in LA, the this is a neutral change.
In any case, analog signs are changes from time to time anyway, so the objection is not new in principle. The simplest solution is then use whatever method was used previously to resolve this.
The big downside is when you park you don't just need to know the conditions when you park, you need to know the conditions for the entire length of your intended stay. You also need confidence that the signs will remain unchanging throughout your stay because if the signs update and you get a ticket the burden of proof is going to fall on you to prove your innocence.