Also, the rf are figureheads - they do not make policy, no matter how much the denigrators claim they have power over how we live our lives
They have enormous influence and ability to shape policy or change things if they want to - but they tend to be very hush-hush and subtle about it.
Even if they never did use their sway or request/demand changes, it's still their absolute prerogative to do so at any time.
Supposing your DH demanded the unrestricted right to sleep with anybody else that he wanted, but he 'assured' you that, just because he now could, he wouldn't - would you think that absolutely fair enough, as he only has the right as a 'figurehead' and will almost certainly (probably) decide never to use it?
Do you not also think that, if they really had no actual power and also no desire to ever use any for their own ends, that would make even less sense for us not to throw it open for an election, or have a trusted panel to decide who the next king or queen was going to be after, say, 5 years?
After all, if it were nothing more than reading out a couple of scripted paragraphs, cutting the odd ribbon and posing for a few photos, why would we so desperately need it to be that same family until the end of time?
At the Festival of Remembrance, for example, every year there are certain poignant and words that are said and pieces of music played every year. These are symbolic, traditional and important to millions of people; BUT it doesn't actually matter who says the words, or carries the flag or plays the bugle. It's obviously a trusted and respected person paying the tribute on behalf of all the public - but most people watching will not even know the name of that person; nor will they want or need to know.
You can't have it both ways: either they do rule to whatever extent they choose to do so, in which case it must be the one family who are supposedly assumed to be the only ones for the job; or otherwise it's all just symbolic, and they are nothing but a nominated representative, in which case anybody could do it.