"If you are saying that "suspension of disbelief" should apply when watching Dr Who, then you are placing the program into the realm of fantasy fairy tales - not the SF the authors would have us believe."
So let me see - a time travelling man who has lived for 2000 years, turns into a completely new person every few years, has two hearts, and said time travel vehicle is 'bigger on the inside, powered by an exploding star caught in a time loop, whose arch enemies include gangion aliens stuck inside a mechanised shell that have no hands or claws that for many years could not go up or down steps, yet somehow manage to be the biggest menace in the universe?
Did i mention that he has a police box that travels back and forth in time, and has a sun trapped in it?
In case you haven't noticed, Doctor Who is firmly in the Science Fantasy genre. along with Star Wars and a lot of the Super Hero stuff, like Superman or Thor. It's not remotely the same as 2001: A Space Odyssey, Battlestar Galactica, or Interstellar, or Star Trek.
Nothing in Doctor Who is remotely feasible, even in a few years. It's just made up stuff to advance the plot.
Get past that, and you'll enjoy the show more.