Protestant means people who reject the authority of the Catholic Church right? So, why might this be too broad a thing to ask about?
If it is too broad, aughtnt we nix the tag?
Too broad for what?
Whether or not that tag is specific enough to narrow a question down to an answerable scope is highly dependent on the content of the question. For many things, yes it is too broad. For some other things, it's quite specific enough.
An analogous situation might be the Unix site. For a general question about where the kernel space vs user space boundary lies, scoping to either "bsd" or "linux" would be sufficient. For a question about a package repository manager, specifying a specific distro such as "freebsd" or "opensuse" is required.
Whether the tag is appropriate or not should be considered on a case by case basis. I don't see a reason to burn the tag altogether: it's not a meta tag.
Using the part of the Mirriam-Webster definition of Protestantism presented in the Protestantism Wikipedia article--"any of several church denominations denying the universal authority of the Pope and affirming the Reformation principles of justification by faith alone, the priesthood of all believers, and the primacy of the Bible as the only source of revealed truth"--I would guess that at least some questions could be answered within this broader context.
(Similarly, Nicene Christianity--an even broader category--would be sufficient for some questions, though there does not seem to be any tag for indicating such a perspective.)
Asking for clarification on a few questions seems to me a lesser price than multiplying questions or losing the recognition of commonality among a larger group of Christians.
Even when there is diversity of views (and divergence from the above traditional Protestant positions), there may be enough commonality that a single answer of reasonable length could provide at least a general explanation.