I think perhaps Calvinism has become the "measuring stick" because of its simplicity. If someone says they are a 4 point Calvinist then we know they reject one point and this opens the way for them to discuss a disagreement (it assumes there are 4 points if agreement).
That said, I do not understand how one could reject the I yet affirm the T, U, and P without a degree of inconsistency.
Total depravity, Unconditional election, and Preservation (Perseverance) can all be held and one not hold to Irresistible grace.
This is not my view, but to allow some expressions that I have run across to explain what others may consider valid.
One can be totally incapable and because of that condition, God extends to that person for His purpose His choosing. That person "kicks against the pricks" as did Saul (Paul) and continues in rebellion. At some point, God's spirit no longer strives and turns that person over preserving them for that destiny in which they desired.
This is not uncommon in the teaching perspective of most non-cal preaching.
That is why they have to engage some prevenient / preceding grace thining.
My personal problem with the term Calvinism is that it automatically presents what may not be accurately held by that person.
I do embrace the doctrines of Grace, but I am compelled (at this point in my life) to separate the elements (facets) of the atonement and recognize some are to all and others are to those who believe.
However, when it comes to thinking of depravity, then how more depraved can one become if they are dead completely in trespasses and sin?
Or when considering election does it become a matter of solely that which is of God without regard to the human condition?
Or when pondering upon grace, conforming to that presentation that the Father's choice is according to His purpose and humankind have no authority to resist?
I am concerned that OSAS presentation to the typical Baptist is incredibly faulty in the sense that folks think all manner of sinful living does not reflect that that person was never part of the tree of life but conformed for the temporary pleasure.
Perhaps I can be convinced my thinking as it pertains to the blood needs to be modified. So far, I haven't been convinced by others' presentation of the Scriptures.