I think it a pity that threads like this are always hijacked by people who feel the need to express views on matters that they had no part in and which took place when ideas, methods, knowledge and people were very different from anything they can have experienced.
AL......
On that basis we would have a very limited view of history. As an example, no one alive fought at the battle of Waterloo but it is possible to research it and then have an opinion about it.
In the case of more modern history we do still have some of the participants with us so they can give their perspective on the event. Others who were not closely involved can still have very valid opinions and it is often interesting to hear them, in this case: the development of the Comet.