They are debuting in the middle of 4th gen which imo is quite late but they seem to have made a name for themselves(for good and bad reasons both lol) even without bighit acknowledging their existence.
Some factors that you might take into consideration:
1. They have yorch (ex thai actor), apparently very popular in thailand, his vlog even trended no. 1 on Yt over there.
2. Woochan (youngest show me the money semifinalist,he was probably 13-14 back then)
3. JJ: dance prodigy basically (the reason why I became interested in them in the first place)
4. 4/7 can speak english
5. Have members that can speak eng, thai, japanese, chinese, korean (aka the biggest kpop markets)
6. apparently self producing( this definitely gives you cookie points among international fans)
7. Bighit (self explanatory and probably the biggest factor)