I have zero issue with Kenobi beating Vader. I have no problem with Kenobi being powerful enough to do so either, or the power displayed in the episode. He's Anakin's boogeyman, and it was an opinion held by at least a few people (myself included) that he would only get more powerful after ROTS.
The problem, imo, is that the progression was laughable. Just like the rest of the show, and a lot of the content Disney puts out today in Star Wars or the MCU, it's a bunch of "moments" strung together that don't make a great story. Or one that even makes sense that much.
I was surprised though, how good the actual dialogue was between Anakin and Kenobi in that scene. Six episodes of shaky shite (bar a few exceptions) and then we get one of my favourite moments in Star Wars in ages. The choreography was weird though, I will say that. At moments they used movements and flourishes ripped straight from their previous fights, and in others they were swinging like they were in the sequels. It wasn't bad, imo, just... weird. And you can explain a lot of it away as being an emotional moment etc.
But yeah, it's Obi-Wan. His stock did rise, yes, but I can't say I'm surprised. And I don't think it lowers Vader's at all, because he's not fought anyone on this level before that had that extra element to it. And I don't think Lucas would have any issue with it either.