I think you are referring to this question, "endure" vs "perdure" vs "persist"
The reasons I decided to protect it:
The question reads more like general reference without any research efforts. I think it should be closed. I thought about whether to close-vote it or protect it and I chose the latter as it is a very old question.
There are two answers from one-reputation users and two deleted answers, all of which are sub-standard. (Please read my comments to the two answers). I judged it is enough to trigger protection.
I judged it would be very unlikely for the question to have a meaningful and well-researched answer from a new user as @tchrist's answer seems to be the right answer.
The only benefit of protecting a question is blocking new users with one reputation or 101 reputation points with an association bonus of 100 from answering a question. Other than that, there is nothing beneficial or non-beneficial to this site.
What I don't understand is why you think protecting a question is doing disservice to this community and why it would deter new members.
There are tens of thousands of questions that are neither closed nor protected.
I have rarely seen good answers posted by new users to an old question. Do you think there is a chance of a well-researched and helpful answer being posted to the question?
Also, you need to note that you have every right to unprotect any question that you find unduly protected.
I just found another protected question, What does "five O" mean (and why)? It was protected right after the second low-quality answer was posted. I don't see any problem protecting this question as it is again general reference.
Low-quality questions always lead to low-quality answers.