I am aware that many people who do not know (much) about buddhism usually refer to Gautama/Shakyamuni when simply saying "Buddha" or "the Buddha" but is this reason enough to have a the-buddha tag?
Originally coming from a Pure Land/Mahāyāna tradition I learned much more about Amitābha than Gautama and so the latter was way less important to me and calling him "the buddha" would have confused and mislead me.
So why not have a proper gautama tag that is used for him?
The only "downside" I see would be that people don't properly tag (let's say they would otherwise...) , but retagging is imo the simplest form of editing and least work. So even this argument won't really hold.
It is rather an argument for changing. Imagine someone using the-buddha and then seeing that it was changed to gautama. When wondering why that happens OP will probably educate him/herself a bit more on why there isn't "one Buddha".