reasons: shorter versions and these were used in the past.
EDIT: i'm not sure if implication of chinese_flag for both is better. but the wiki of republic_of_china_flag tells it should not be confused with the chinese_flag which somewhat clashes in the flag wiki.
Except the Republic of China ruled over mainland China until 1949, and as such during the period of their control of mainland China it was also very much the Chinese Flag as well. Effectively both flags are Chinese flags.
Aristocrat said: "Republic of China" is Taiwan. "People's Republic of China" is the mainland China most people think about when they hear "China".
That also depends on where you live. What you say probably is the case for most Westerners, but the Mainland Chinese typically have a different mindset. Taiwan's sovereignty can often be a touchy subject.
as if by fate, i encountered post #1018495 just now. the flag opposite ROC flag looks like the first Republic of China flag in 1912. it had a name though, akin to Union Jack of UK. it was called "Five Races Under One Union" by wikipedia. should this implicate chinese_flag as well? as historically, it covered the mainland too.
Keep things simple and keep the flags separate. While China insists on calling Taiwan the Republic of China, no one else does. And please, no implicating flags to other flags, sheesh.
as far as i remember, the prc_flag and roc_flag were used as early as october last year (but need some rechecking). the longer names are recent but yes, descriptive and someone already edited the entries. there are not really that many. my aliases suggestion are merely a request for convenience than typing a mouthful and hopefully prevent creating separate entries for the same flag (saves time from editing).
since there are 3 types of chinese flags now, i might consider using "Flags of China" or "China Flags" or plain "China" in the flag wiki and place the 3 flags below it.
I think it would be better to keep it as the republic of china flag, as opposed to taiwanese flag. The flag is very much a valid flag of china, and it is the flag of the country "The Republic of China" which just so happens to still exist outside of mainland China. Given that we do get images of WWII, and it isn't exactly the rarest topic to make images on, it wouldn't be inconceivable to find a WWII referencing image that would use the Republic of China of flag in it. It would be rather odd that the flag is then tagged "Taiwanese Flag" when in such an image it would have nothing to do with Taiwan. In short, there are plenty of areas in which the flag may be used in a historical context that would have nothing to do with its tie to Taiwan.
Keep things simple (...). While China insists on calling Taiwan the Republic of China, no one else does.
I do, sometimes, and I certainly have no political reasons to side with either of the countries involved. To me, Republic of China, in contemporary contexts, is simply the longer and more official wording for 'Taiwan'. Using republic_of_china_flag is in line with the Danbooru practice of using the longest available name variants for character tags.
While you have a point, I am siding with Renim's argumentations here.
I removed some of the material added by Henmere, believing that the Chinese spellings are easy enough to find in Wikipedia when needed. Feel free to add them again if you find them important.