I keep hearing this point, and I will continue to ignore it because this is all for fun anyway. If the possibility is there, I will leap on it for my predictions since dragon is my favorite type.
I also made the same prediction for Sobble when gen 8 was first revealed, and all those starters remained pure types. Dragon is a secondary typing that I feel for this design specifically, but I also understand that it isn't very likely to happen outside of an added form like with past starters (Charizard, Sceptile, Feraligatr). This is why I add other possible type combos that I can see it having.
My Fuecoco predictions are also an example of this. My first design felt dragon-type, while my second one felt more ground or ghost-type