Of course I can.
When the Nazis wanted to round of Jewish people, it wasn't that difficult. They started with neighborhoods. Then they went door to door, had made lists based on church records. They also looked a book store receipts. Interviewed people at meetings, followed up on tips for dissidents.
I don't think this would have been any worse with today's information technology. As technology increases... the basics of life haven't changed. We are still making art, visiting family, listening to music, arguing about politics, buying crap we don't need. Technology has changed a little bit about how we do things.
The main change of technology is that we can do the same things with less labor
. We haven't gotten rid of media, or journalism. We just now produce it with far fewer typists.
The Dictators are going to do with Dictators have always done. The Chinese purges, the Soviet purges, the Nazi purges, the Spanish Inquisition and hundreds of related witch hunts and racial all took place and were all very efficient.
The change with technology is that instead of sending inquisitors door to door, they can now look up information on an electronic list. But they will do the same things with perhaps less labor.
You are saying that modern dictators will be able to do things that the Nazi's and the Inquisition couldn't do. I do not believe that this is the case... not even of extent.
Kim Jong Un has a complete stranglehold on his country. No technology is needed, just an overwhelming fear backing a personality cult.