This is of course quite similar to what Tolkien had argued back in 1944, where the opening section of his unfinished Time-travel novel, THE NOTION CLUB PAPERS, argued among other things that good science fiction had to hold itself to a standard of scientifically credible fact and singled out starships as an example that failed to meet that criteria. I was away from my books at the time, but now that I'm back at my desk I've searched out some of the salient passages, which are given below.
The chief omission in the following wd be that I've left out the various speakers' names in the give-and-take of the original discussion; these are readily available, for anyone interested in these specifics, in Tolkien's original text (in HME.IX.143ff).
THE NOTION CLUB PAPERS: Night 60
. . . no one has ever solved the difficulty of arriving, of getting to another planet, no more in literature than in life. Because the difficulty is in fact insoluble, I think. The barrier cannot and will not ever be passed in mortal flesh [.162–163]
An author's way of getting to Mars (say) is part of his story of his Mars . . . It's part of the picture. 
I'm talking about credibility . . . I don't think space-ships [exist], or could. And anyway, if you pretend they do, and use them for space-journeys . . . they'll land you in space-ship sort of adventures. 
I want to be made to feel that the author has faced the difficulties and not ignored them. 
Any one who touches space-travel now has got to be much more convincing:* if indeed a convincing machine is at present possible . . . the problems have become more complex, and not simpler . . . A gravitation-isolator won't do. Gravity can't be treated like that. It's fundamental. It's a statement by the Universe of where you are in the Universe, and the Universe can't be tricked. 
Scientists are as prone to wishful thinking (and talking) as other men. 
[touching lightly on effects of zero-g (and greatly increased gravity)]: I . . . find it difficult to believe that a machine like our body, made to function under definite earth-conditions, would in fact run on merrily when those were greatly changed—and for a long time, or permanently. 
I don't doubt the possibility of sending a rocket to the Moon . . . I'll even admit the eventual possibility of landing undamaged human goods on the lunar landscape . . . But the Moon is very parochial. Rockets are so slow. . . . even the speed of light will only be moderately useful . . . you'll have to plan for a speed greater than light; much greater, if you're to have a practical range outside the Solar System. Otherwise you will have very few destinations. 
[to sum up]:
[Question]: people cannot leave this world and live, at least not beyond the orbit of the Moon
[Answer]: I believe they could not, cannot, and never will 
[Conclusion]: a space-travel story ought to be made to fit, as far as we can see, the Universe as it is.
--current reading: a Dorothy Sayers festschrift (1993)
*the reference here is to H. G. Wells' Cavorite, which had been part of the Notion Club's discussion