The earlier answer by @slm had addressed particularly on my deleted question. Just one thing is missing: There was no apparent reply for "what is a better way to ask such question?" part. I think answering the latter part of question is necessary, in case future-me or someone else decided to ask similar questions later.
In the following text, I have included some points to help anyone to justify whether historical questions can be asked or else, as well as whether historical question can have objective answers or not.
Can I ask the question
Yes. Historical questions can be asked to clarify the known facts and usually have some amount of information that could be written into objective answers. Unfortunately, not all facts are well known or properly documented in place. This will bring to the next point.
Can I get the answer
Yes and no. Given that most information could be collected by the Five Ws, the question will likely have an answer and therefore a yes. However, given that limited access to the information due to lack of documentation and publication, the question might not have any answer and therefore a no.
Can I have the answer anyway
May be, as long as the question is not closed and answerable. When existing resources are limited, there are several ways to increase the chance to get the answer. One way is to send a direct enquiry to the developers or the members of the project; Another way is to hope that any user with real experience could explain about the subject.
The following posts on Unix & Linux SE are relevant examples:
As a result, the question may become answerable. That being said, these are not sure-successful ways to get the answer; Both ways depend on whether people are willing to provide information and put that into an appropriate answer. For serious askers, one's willpower and patience are required for finding the answer.
When to delete the question
I had waited for almost a year before I had to give up on my historical question. I had concluded that it was not answerable due to the "lost history" of SYSLINUX (or ISOLINUX to be exact).
To this answered date, this article on Wikipedia had very less information on the history of SYSLINUX. Not even the project page had mentioned anything relevant. The oldest page I found from respective sources were created in 2003 and 2006. In contrast, SYSLINUX supposedly had existed since 1994. The gap spans between 12 and 14 years, which I referred as the "lost history".
If such question had been asked and remained unanswered, one may try rewording the question in other way of relating the subject. Although, historical questions are quite straightforward that leaves very little room to rewording the question.
Then again, if such question had been asked, remained unanswered and then closed, consider to delete the question as recommended by @slm.
A better way to ask
Prior to asking historical questions on this SE site, the subject of interest must be identified and the basic information can be accessed by the public. If some basic information are already missing from beginning, it might be better not to ask here. And if such question is posted anyway, it may be closed for any reason.
So a better way to ask is perhaps, by not asking such question. Keep the question to yourself, then after some time, review and determine whether the question can be answered or else. This way, it is better than directly posting the question here, only to find later closed by the community and yet, disappointed by having no answers.
TL;DR Most historical questions could have objective answers. Lack of basic information indicates that some questions might not be answerable. Perhaps better not to ask such questions in Q&A format; Find other ways or give up instead.