Why can it not be? Yes, some suffer greatly on earth, and it is commonly said that they suffer their Purgatory here, but how does that preclude it after death?
"Why can it not be? Yes, some suffer greatly on earth, and it is commonly said that they suffer their Purgatory here, but how does that preclude it after death?"
Indeed!
There is much hidden wisdom in this statement.
Think of the agony of the "good thief" on the Cross.
The Bible does not tell us his sins. It merely says he was a rebel. Maybe he was a killer. Maybe he just flouted authority. Maybe he was a theif. Whatever, he was being tortured to death, and that's a big balloon payment on sin, isn't it?
Most deaths are horrible, wretched affairs. Today, it's long lingering in pain in the hospital, or terrible trauma in crime or accident. Some few have mercifully short deaths but for most people death is a long and painful process.
Remember that we have those hospital studies of the clinically-dead-brought-back. They report the afterlife. For most, the experience is pleasant; for some, it is not. They tell of the life review.
To the extent that we do have to pay for unrepented sins, or repented sins (if the Church is wrong about plenary grace for sins confessed and wiped clean), Jesus told us that the standard of judgment was that we should be judged as we have judged. So, the same sin may merit different punishment depending on the degree of relentless judgmentalism and unforgiving harshness of the sinner himself in life (think Lamech).
The truth is we really don't know. There are a bunch of different visions of the afterlife given in the Bible. Jesus' is clear and straightforward about what one must DO and BELIEVE in life, and what the afterlife brings. I say: cling to that, and do not be confused by the other doctrines. And I say be a fair and compassionate judge. And I say confess and repent often, and do those things Jesus said to do.
More than that Jesus didn't ask.
He also didn't demand LESS than that.
The wedding cake of doctrines piled atop other doctrines is confusing and seems to get Christians fighting with other Christians more than being charitable.
Still, Jesus referred to Hell and Purgatory in one word: Gehenna. Therefore, it is. Staying out of both so as to not have to figure out the gradations of these things would be the better course.