Then the question becomes how do you determine "guilty beyond doubt"? Where is that line drawn?

A perfect example would be eye witness accounts. To a lot of people, that's the most important thing. Well eye witness testimony has proven over and over and over again to be entirely unreliable. It's basically no better than any other he said/she said.

Video? Well that becomes a problem very quickly with the emergence of deep fakes. And let's not even act like that matters anyway. Check out the Amaud Arbery discussions for how a video of a murder doesn't appear to be a video of a murder to so many people.

Concessions? Coerced confessions are a huge problem. Confused suspects misspeaking leads to "confessions". A confession from a fall guy becomes a problem on occasion.

And so on. Although most modern justice systems are supposed to rely on the idea of beyond a reasonable doubt, there almost is no such thing. If not for plea deals almost no one would be behind bars for violent crimes.

And that's not even getting in to one of the few instances where the slippery slope comes in to play. I guarantee people in this comment section will say it is acceptable for rape. But the definition of rape varies widely. Does it have to be violent? Does it have to be a man? Does it have to require penetration? Does sodomy qualify? Those are all questions that actually apply to different state laws in the US.