The problem is that there are a large number of questions about prototypical inheritance on Stack Overflow, because it is rather an unique language feature, and it would be useful to be able to look at questions about it just like one might use the oop tag. However, these questions are now buried under questions about the Prototype framework, which sees a larger volume of questions (at least in its early days; jQuery now dominates)
Unfortunately, as far as I can tell, this wasn't sorted out earlier (with the only discussion on the problem being this: Is the SO prototypejs tag correct?), so now we have to deal with this mess with more than 2200 questions tagged prototype and 400 tagged prototypejs. Oh, and don't forget about the 102 questions tagged prototypal-inheritance.
In addition to that, the prototype tag wiki states that the tag is used for questions about the library, but that would mean that there are now two tags for questions about the Prototype library, which is highly undesirable, and in addition to that, the tag prototypes is synonym'd to that tag, and you would never use prototypes for question about the Prototype library, and of course, no unique tag for question about prototypal inheritance. So... yeah, it's an almighty mess.
I propose two solutions, neither of which are desirable (because of the amount manual intervention needed) but here goes:
Since there are more questions about the library than about the concept, retag all questions in the prototype tag that are actually about the concept to prototypal-inheritance, synonym prototypes to prototypal-inheritance, and merge prototypejs to prototype.
I would like for a vote on which of these solutions to adopt, to put this problem finally to rest. Or maybe another solution exist, which I would appreciate being put into a new answer