Wikipedia:Protecting sections of a page

This is my first proposed policy, so if it has already been debated and rejected, please don't bite me.

The policy would allow the administrators to protect a section of a page, rather than a whole page. It would be accomplished by adding a (what I assume is relatively simple) bit of programming whereby new tags (which are {protect-section} and {end-protect-section} or something) can be placed at the beginning and the end of a part of the text of a page.

From when they are placed to when they are removed, a box (much like the disupted section template) would also be there added, with words to the effect of "this section of text is currently protected. This does not endorse the current version". And indeed, that part of the page would be unedittable. The notice could be removed by removing the tags, and of course only administrators would have this power. I so not think (although, not being a techie, I would not know) that this would be hard to achieve.

The great advantage of this policy would be that often, disputes over a page centre around one section - or even, in the case of the Apartheid page, one word - and protecting the whole page stops the uncontested parts being updated and improved. Protection stunts an article's growth needlessly, if only a short part actually needs to be protected.

So there it is. Now, please tell me why it would not work!