I really don't like the justification that if Raimi wasn't forced to do "Venom", SM3 would've been good. I think the movie had plenty of issues that were bad and I actually don't think Venom was that poorly handled (though Peter wearing the symbiote, that's entirely different).
The Sandman retcon, which wasn't even hinted at in previous movies, alone ruins whatever good the series had built up. It just tells the audience that nothing that happened in those other movies will ever matter because we can just make some random shit up.
At least in the modern MCU era, Marvel is more about pushing soft retcons so old films that might seem out of synch line up a bit better (Cap 2 did a lot of this, though most of it isn't noticeable on first watch).