I can speak for myself and why I voted to close. First, let me note that I voted to close as "Not a real question", as did 3 other voters. It just so happens that a mod's choice of close reason trumps that of others and hence it looks like we all voted to close as "Too localized". I do not think it fits the localized description, but I do agree with:
It is difficult to tell what is being asked here. This question is ambiguous, vague, incomplete, overly broad, or rhetorical and cannot be reasonably answered in its current form.
I must, at this point, urge the OP to not read into the above sentences personally, but objectively as these are the system's stock descriptions for close votes.
Coming to the question, here are some observations:
the title asks "Why is WolframAlpha more intelligent than Mathematica?" while the body offers no reason as to why the choice of adding
==0 to whatever is specified is an "intelligent" option. As several commenters have observed,
==0 is a rather arbitrary choice and might make sense in a program like W|A, which needs to take into account the fact that the average user might not necessarily know how to state it mathematically or know W|A's syntax. However, in a programming language, such "interpretations of intent" will result in ambiguity and is often undesirable.
I felt acl's answer showed how one can, if they so desired, program rather loosely with Mathematica by getting W|A to interpret its input. But the OP dismissed it and insisted on knowing why Mathematica can't interpret itself, which wasn't what the question asked.
The confusion started when the OP started posting a series of comments and update to the question along the lines of "It is not about syntax or mathematical ability of the user", which made people wonder what it really was about then. There were some more comments on using Mathematica's intuition and guessing in debugging... It was also mentioned that the existing scheme provides an excellent way to debug by generating an error message and pointing to the docs.
Finally, after it was closed, the OP mentioned that they thought their question was correctly worded to mean "Is there an option?". Well yes, that was in the question, but given the title and the additional ambiguous comments, it wasn't clear if this really was the crux of the question.
It is very easy to ask "Why is X so?" or "Why is X not Y?" but it is harder to justify why the "Why..." question is important. This is the distinction between a question that arises from idle curiosity (often construed as a lazy question, placing the intellectual burden solely on the answerer) and one that has been given some thought and consideration with reasonable arguments (often construed as a good question that shares the intellectual burden, even if it is unequal). The latter is what makes a question's purpose clear and motivates an answer and makes it a good fit for this site.
Now in light of Daniel's comment, it looks like the OP is trying to reposition their intent as being focussed on the technical aspects/limitations/design considerations etc. of having such a "feature" in Mathematica. This is patently not the intent of the question, at least not of the one that has been asked, without having to resort to mind reading.
This brings us to the OP's choices (in my view):
Rephrase the question body and title to better reflect what exactly they're after (now that they have additional info). Perhaps gear it to the specific details so that DL could provide an authoritative answer (to the extent he can) on the implementation details.
Let this question run its course (eventual deletion sometime in the future) and ask a fresh question that asks for technical limitations and/or design considerations.
I would suggest the latter option.
At the end of the day, I don't think any of us (I certainly don't) rejoice in closing questions. However, it is necessary at times and things are always done with the community's goals and interests in mind. So given my views above, I would not vote to reopen the question as it stands. However if the OP were to follow the suggestions and rephrase their question, I would gladly vote to reopen.