I've never really been a fan of the whole 'this is how we used to do it' type of argument, because it's typically nothing more than anecdotal. My experiences playing in a server may be completely different from another person's, depending on an infinite amount of factors. Anecdotes don't really mean anything, which is why it's always good to reflect back on what's actually in writing and posted.
While I'm not dismissing that admins have, in the past, punished players for things they did not witness, I'm going to comment specifically from my eleven years or so of administrating the servers, managing servers, managing the community, and ultimately being the Generalissimo (from a factual standpoint, not an anecdotal one). There has never, to my knowledge, been any type of sanctioned policy where admins are allowed to just punish people based on nothing more than hearsay and circumstantial evidence. If someone can find some sort of written rule that says something to the contrary, please let me know. Even referencing the original 'Admin Rules' thread made back in 2009, there is nothing in there listing where that is allowed.
At some point in time, whether gradual or rapid, certain admins took it upon themselves to start punishing players based on the aforementioned. This led to an increase in admin complaints, to the point where it was rapidly becoming an onset issue: the juice of letting admins investigate is not worth the squeeze of breaking down the multitude of legitimate complaints that follow for admin misuse. If an admin uses their power in an incorrect manner, to include punishing a player that they have no idea on if an actual rule was broken or not, they are (and always have been) subject to punishment. Plenty of strikes have been issued for admins doing this. While we're not here to really investigate admins on if they knew the player committed an offense, if a complaint is submitted from the standpoint of the person being punished and it is clear there was no wrongdoing on their end, the admin is at fault - whether or not they were acting with honest intentions. Us stating 'stop doing this' is literally nothing more than a reminder that it shouldn't be happening in the first place.
I'm not going to go into hypothetical situations on why punishing off of hearsay is a bad idea; that's been outlined several times, and me repeating that isn't going to get the point across if it isn't already there. I will reiterate though that it has never, in the history of SG, ever been okay for admins to punish people based off of anything shy of concrete wrongdoing. I'm sure most of us have done it at some point in time or another (myself included), but that absolutely does not mean that it was the right thing to do, nor that it was an established policy.
This is not something that will be changed, as the bad outweighs the good...by far.