One response is to answer by saying this "bug" is considered a "feature". AAAAaand when you trigger it, it's hard to see that it even serves a point, but it does...
Virtually the same warning/error was discussed several years ago; this question is a duplicate, in a sense, of:
When a user wants to delete their question, don't *let them click delete, then show them this long message asking them to think it over if they actually can't delete it, since it has answers by others.
A new/refactored answer felt worth creating, as I puzzled this out myself. The rationale rests on multiple partly-redundant legs.
Apparently, without being a mod, it's hard to appreciate the amount of time that is spent responding to folks requesting question deletion wherein the mod essentially thinks the folks all "should have known better". That may sound odd. What I've realized is fair to say is that the claim that "any question (that
doesn't break the rules) has value" is true enough that a system that
defines/treats it as 100% true is a good thing. One can argue that with enough editing, any question can have some salvage value. It may involve more or less deleting and replacing close to all of it, and may cause its answers to lose value. But if it's not true for 100% of questions, it's close to.
It's believed that on average, it helps preserve moderator time by particularly effectively convincing people who want an already-answered question they asked deleted to change their minds or give up, ideally both.
I do think valuing moderator time highly is important, but still does it really give license to program the system to be deceptive and a **** to people? Not in my eyes, but apparently - doing so has been the status quo, and defended even though the message is usually flat out misleading the reader. Perhaps the message can change to reflect the don't be a **** to newbies efforts that the leadership has been heavily emphasizing, without failing to serve, or perhaps even better serve, it's other purpose.
I read that doppelgreener, on May 29 '14, turned it into a feature request; it's worth revisiting; I agree with Catija♦'s much more recent answer. The issue has become worse in that "Delete Question" is now red (a fake warning).
How 'bout . . . (additions bolded):
We do not recommend deleting questions with answers because doing so deprives future readers of this knowledge. See "I've thought better of my question; can I delete it?" for the answer and alternatives to deletion.
Repeated deletion of answered questions can result in your account being blocked from asking. Are you sure you wish to attempt deletion?
[Attempt to Delete Question]
Clicking "Delete Question" is (where not allowed) currently followed by:
You cannot delete this question as others have invested time and effort into answering it. For more information, visit the help center.
This is OK/an improvement from what yuritsuki encountered in '14.