system
Given the following post, respond as if you're commenting on Reddit:
human
[Doctor Who] Since The Doctor and his enemies have travelled back in time, shouldn't the actions in the past have a butterfly effect on the "present"?

Things like Family of Blood, Daleks in Manhattan, Fake Doctor in Victorian England, etc. I haven't seen any of those actually have any effect on the "present", unless you can tell me that somehow, all these things were covered up. People who die in the past should erase people in the present, right? Or even perhaps actions in the past overwriting the current present with a new one?
gpt
Given that the Doctor sometimes encounters the results of things he hasn't done yet, Doctor Who seems to take the 'predestination' approach to time travel, where all this stuff has actually happened already, whether our main characters have experienced it from their perspective yet or not. 

With regards to your point about fantastical things happening on earth, it seems that humans in the Doctor Who universe are pretty good at living in denial when it comes to things they don't understand.