Just as the Carnage links were pretty coincidentally allowed to come out (call me a cynic, but studios DEFINITELY still release information they want to get out there to help shape the conversation), there was a LOT of talk about Venom's potential links to the MCU.
Despite the fact that the Sony/Marvel deal seemed to make such a link-up impossible and that Ruben Fleischer has admitted since release that NO conversation about an MCU link ever happened, Sony knew that talk was good for their movie. Look at the release date of Venom for further proof: rather than waiting for Spidey's MCU time to be done, they decided to piggy-back on Marvel's marketing juggernaut, knowing that Spider-Man: Homecoming's success would make anything even TENUOUSLY linked to Tom Holland's Spider-Man profitable.
Fake news goes a long way in 2018 and there's a reason we were all led to believe that Holland might even have a cameo in Venom. There's also a reason why the conversation about whether Venom counted as an MCU movie went back and forth for seemingly months in the run-up to release and why Amy Pascal used that curious "adjuncts" term to categorise the Spider-Verse spin-offs. Even as Kevin Feige was saying there was no link, Sony's marketing engine was grinding against that - they WANTED us to expect a link and why the hell wouldn't they?!