I think many people confuse free will with learning. That is, we can learn from our mistakes and then claim we would have done differently in the past.

The kind of free will I object to is the version that claims if the movie of the universe (including me) were rewound to a previous point, I could have chosen differently than I did. But if I were rewound, then I'd've lost the learning from mistakes since then.

If every quantum particle were rewound to a previous state, then (barring stochastic and quantum effects) everything would have played out again exactly as it did the "first time", including my own actions.

The reason I object to it is because there's no scientific basis for it, and lots of evidence against it.

And I strongly dislike the "illusion of free will" thing, because I strongly dislike illusions of any sort. I'd rather have an unhappy truth than a happy illusion.

But that's just me.