I haven't noticed people hating on the concept of alternate history, though it can certainly be done poorly.
Some potential points of failure are:
1) The alternate history is poorly researched, such that players who have done even light reading reading on the subject find it to be just grossly wrong. Ideally, reading up on the subject era should pull players in deeper and inspire character concepts and adventure seeds.
2) It is unclear where the alternate history is departing from actual history. This can be because the historical period is one that players are unlikely to be familiar with, or because the author has not communicated the point of departure clearly, or because there are multiple points of departure whose effects are complicated and/or arbitrary. In all cases, the effect is that the GM frequently interrupts players with "you can't do that" or "it doesn't work that way."
3) The GM plans to use a historical event as a surprise pivotal event, and the players discover the event before it happens in game. For example, in a pirate game I ran, my players did some reading and quickly discovered that Port Royal would be hit by a massive earthquake in 1692. It wasn't a game breaker, but nobody bought a house in Port Royal.
4) The GM puts way too much of their own personal politics into the game, and turns it into either a screed, an indictment of the players, or a fairy tale.
5) The GM uses history, either actual or alternate, to railroad the players or push them onto the sidelines. The campaign should not end with "you all die, but at least you gave the real heroes some pluses."
In a lot of cases, just setting the rules out for the players at the start of the campaign will do a lot to avoid these problems.
For instance, when I ran my pirate game, with African-American players among the party, I knew that the issue of slavery could threaten to derail our fun on the high seas. I told the party up front that yes, historically, slavery existed, but nobody was allowed to be a slave owner, and I wasn't going to bring it up or make it a primary theme of the game. This was an acceptable compromise.