In EU they are not allowed to consume more than 0.5 Watt. And this regulation has been in force since 2008.
Since mostly everybody design for that, I expect this norm also benefit other countries. So this is not really an issue, unless you are in a country without such regulation, and you buy some cheap off brand charger.

…europa.eu/…/standby-networked-standby-and-mode_e…

Since the standby power is so low, the wear is most likely insignificant too.
Having an idle unit that uses 0.5 Watt on constantly for a month, consumes about 1/3 kWh, but since this regulation has been in force since 2008, I suspect idle is improved further for most devices. 0.5 is a maximum allowed value, and most would prefer to stay below that to not get into trouble.