Honda made it standard way before anyone else. I know by at least the mid 90s they already had the voltage regulators (ELD). Alot of newer cars have adopted it, car makers do it because it slightly pads the MPG ratings.
Depends. On my Honda that trick would work but id never see above 13.8 even with the ELD on full tilt (usually with the ELD on i'd be 13.3-13.8 range while driving with no music on). Moment I threw in the Singer Alt which had the ELD bypass built in I was immediately seeing 14.8V
I don't see the point in Mechman selling an expensive aftermarket electrical upgrade and then basically saying "yeah sorry it's only going to run at 80% potential because we don't want to bypass the PCM"