A few comments:
1) I've seen a few people point out his numbers in AAA, but I don't think I've seen much optimism beyond that. Do you mind quoting the posts you think are unreasonably optimistic?
2) Literally nobody here cares what people on sportsnet or reddit think.
3) IIRC my opinion on Gurriel over the years as gone something like:
2016 - cool, the Jays signed a highly regarded prospect
2017 - damn, Gurriel isn't hitting very well
2018 - ok, the bat looks like it might be average. if he can defend at an average level he'll be a decent player
2019 - f***, the defense sucks and he might not hit enough to make up for it
So yeah, my opinion has evolved over the 2-3 years he's been in the org. Of course it has. He was signed as a huge-variance player out of a situation with literally no information on him as a player.