I have serious trouble believing anyone in the physics community actually believed rockets wouldn't work in a vacuum. The principle that allows them to operate there is Newton's Third Law, which by the 20th century had been around quite a while.
True, random people off the street may have believed that, but random people off the street today often have trouble figuring out why jumping in an airplane doesn't ram you against the back wall. So personally I don't think opinions of the subject-matter ignorant should count that much. The problem comes in when you rely on such people for your funding.
I do think you are slightly misreading the quotes in your linked article1, but you came by it honestly because you were meant to misunderstand in exactly that way. A cynic might argue this is journalists glossing over the minor fact they caused the problem.
There are two parts here. First off:
Too often the word "impossible" is used by people who lack the imagination or even the knowledge to understand what is being attempted.
IOW, we are talking my proverbial random people off the street here, not people who actually understand physics.
Then there's this (quoting Goddard):
The subject of projection from the earth, and especially a mention of the moon, must still be avoided in dignified scientific and engineering circles.
Nowhere does it say "because those circles think its impossible". The article implies that by placing those quotes in proximity (so bad on it), but I don't think that's what Goddard was saying. He was referring to public perception making it tough to get things like funding and publication. He had trouble getting taken seriously because the general public associated his rockets with cheap Sci-Fi.
In the early and mid 20th century Science Fiction was largely cheap schlocky paperbacks, and had only slightly more cachet than Romance novels. It was looked down upon by pretty much anyone "serious"2
Gooddard mentioned the moon in an aside in a large report on his rocketry research. Some ignoramus (obviously not an actual physicist) wrote an anonomous Op-Ed to the New York Times, ridiculing the entire research based on this tiny bit, with indeed the claim that somehow Newton's Third Law doesn't work in a vacuum.3
After the rocket quits our air and really starts on its longer
journey, its flight would be neither accelerated nor maintained by the
explosion of the charges it then might have left. To claim that it
would be is to deny a fundamental law of dynamics, and only Dr.
Einstein and his chosen dozen, so few and fit, are licensed to do
This article had no small effect on history, as the public ridicule caused others in the USA to avoid Goddard and his rocketry research. For what its worth (almost nothing), the Times did eventually publish a retraction ... in 1969.
Further investigation and experimentation have confirmed the findings
of Isaac Newton in the 17th Century and it is now definitely
established that a rocket can function in a vacuum as well as in an
atmosphere. The Times regrets the error.
1 - On the first page of your link. I actually couldn't find any mention of space travel on the other articles under it, but that could be my old eyes.
2 - I can remember in the mid 80's being specifically told by an English prof I could read and write a report on any book I wanted, but it shouldn't be Romance or Sci-Fi because those weren't "serious literature". I got ticked off and wrote a 20 page mini-dissertation on the themes in Dune
3 - Notice this also including a reference to the Urban Legend that almost nobody can understand Relativity. As an indirect result of this letter, it was the Nazis who ended up picking up his research and making the real advancements in this field. Really I can't say anything bad enough about the anonymous coward who penned this.