Here's John Owen, the Calvinist: "But indeed Christ has no such power, no such ability; he cannot save unbelieving, impenitent sinners; for this cannot be done without denying himself, acting contrary to his word, and destroying his own glory... Christ is able to save all them, and only them, who come to God by him. Whilst you live in sin and unbelief, Christ himself cannot save you".
Owens Works Meditations and Discourses concerning the Glory of Christ (Location 10334 Kindle version).
If you mean irresistible grace like that then obviously you are misunderstanding something, or Owen is not a Calvinist.
Now let's look at who these folks are that are excluded from the atonement. Once again I'll use Owen, just a couple of paragraphs later than the above quote: "There is therefore no man who under gospel invitations, refuseth to come unto and close with Christ by believing, but secretly, through the power of darkness, blindness, and unbelief, he hates God, dislikes all his ways, would not have his glory exalted or manifested, choosing rather to die in enmity against him than to give glory to him. Do not deceive yourselves; it is not an indifferent thing, whether you will come in unto Christ upon his invitations or no, - a thing that you may put off from one season unto another: your present refusal of it is as high an act of enmity against God as you nature is capable of."
I think the "5 points of Calvinism" or the doctrines of grace were in answer to doctrines that were believed to be in error by the Arminians. You see Calvinist beliefs above that don't agree with your conclusions regarding Calvinistic theology. Why do you keep insisting that Calvinists have to interpret these things as you wish, rather than looking at what Calvinist preachers said? Clearly, in Owens words above you see a lot of "free will". But apparently it is not the same free will as you view free will. I would look there for answers.
Apparently that is not the whole story. You are demanding a level of autonomy that goes far beyond the average Baptist non-Calvinist preacher. Above, in Owen's quote: "but secretly, through the power of darkness, blindness, and unbelief, he hates God". Does that sound like an autonomous free will that can truly evaluate and make a proper "decision", or does that sound like someone who has an impaired free will, dare we say "depraved" which, is truly free in that he can certainly do what he wants to do - but he sees no value in Christ, has no concept of his sin before God, and even has animosity towards anyone suggesting differently - and so needs help. Maybe that "help" is conviction, or "enlightenment" or maybe it's a new nature, but there is more going on than a free will choosing wisely.