The central issue here would be that some human cooperation is needed in sanctification and not everybody sees that. We are made holy WITH our consent and cooperation. Otherwise we remain carnal and quite unholy. Maybe saved, maybe, but not mature in Christ, and no renewal of our minds. But only the fully sanctified are ready to see God in the beatific vision. So one way or another if we are saved we still need to be sanctified. We can do that in the here and now or we can put it off but it will happen. At least it will happen for the saved. Those others do not need sanctification for where they are going.
So we look at people, and we cannot judge their souls but we can get a clue enough to guess at sanctification. Enough to guess at the pitiful levels of our own sanctification. And we know that big Mack truck with our name on it might be just over the next hill. How do we, who are not very sanctified, get that way before we get to crest that next hill. What, some gargantuan act of faith? If you one has never had a 'come to Jesus' moment that would be a very good idea. Quickly before getting to the top of that hill. But then comes the work of being a disciple, of acting on a new faith, of repairing the psychic and interpersonal and creational damage that is very evident in everybody and everything around us. So we start a life of reparation in the time we have left. We get to the top of the hill and there is the Mack truck. The reparation continues nonetheless. That's purgatory.
The reason some just cant grasp it is because they have it in their heads that Jesus already did it all without our need for consent or cooperation. Saved, sanctified, renewed in mind, with zero bad habits remaining, zero imperfect attitudes, no debt to anyone for past sins, it's all perfect. In their minds they are ready to stand before the holy God forever and they are ready to tell God to open the door so they can behold Him. They have arrived. They are ready. They don't need a moment even of preparation.
I wish we were all that sanctified. I don't know how many of us are, but I'm betting it's vanishingly few. The rest of us have to cooperate with the abundant grace of God to get to that point. And some of us need more time than we actually have.