Which goes back to the powers being divinely granted which isn’t what 5E says. My Innkeeper can just swear an Oath to themselves and gain power.
It does not go back to that. The oath can be tapping into something ambient, external,
sacred, while still being
personal.
Just because something arises from a personal choice to dedicate to something, does not mean that the results of that dedication are now somehow
exclusively derived from within the self. But that false conclusion is the only way you can get to "swear an Oath to themselves and gain power."
They aren't swearing an Oath
to themselves. They are simply swearing a capital-O Oath. And such Oaths, when real and true,
are power, in and of themselves. The overwhelming majority of little-o oaths do not do this. They do not have the commitment, the purity, the
severity that an Oath has.
Breaking an oath simply has consequences because you feel bad, or others may learn of your failure to uphold it and thus think less of you. Breaking an Oath actually
costs you.
