You're on to something with this. A browser extension that ran as a local app and made it very clear that it was local would be very attrractive to me. The only worry I would have would be over whether it would eventually grow and grow like the bitcoin blockchain. I lost interest in both Bitcoin and Dogecoin not because of the basic concept but because I got sick of hosting multi-gigbyte clockchain files, and the binaries were so poorly designed that they don't even give you an option of where to store your blockchain files in a config screen, and just stick in in a subfolder on the boot drive where the software was installed. Sure, I could get around that, but the thoughts that run through my mind when I find myself unexpectedly running out of space on my boot drive are a) life is too goddamn short, and b) if they didn't make that very basic thing easily configurable what other problems am I going to run into?