I did enjoy that episode. However I go into it looking for a bit of relatively light entertainment.
I'm not looking to much and am no writer or director so I'm not even thinking about the creation side of it. Some people these days think they are able to judge a writer or director as if they are amazing at it. Happens on so many forums and threads I visit.
If you'd do a much better job, then why are they not a script writer?
I'm not sure they are comparing writers to themselves (non writers), I think its more that they are comparing the writers to other writers.
For example, if I say that British tennis player Patrick Foley (ranked 1,847th in the world) is naff, its not because I think I can play better tennis than him , because clearly I cant, its because compared to his fellow tennis players on the world circuit, he's naff.
Part of this is of course dependent upon the genre you put Doctor Who into, if I consider it within the context of childrens entertainment, then the writing is sufficient. If however I consider it within the context of sci-fi entertainment , with it having to then stack up against the sci-fi writers behind The Expanse, Black Mirror, Stranger Things or Westworld even, then it fares much much worse.
I guess the gist of what I'm saying is that the old argument of "well you do better" , isnt always applicable because it may not be valid in terms of the criteria that the critique is based upon.