The thing is that no matter what you think and no matter what wikipedia says, the non-numbered titles (aside from Coded) are considered mainline by both the creator AND the fans. No matter what you say, that won't change, you can keep linking that wikipedia page all you want but what the creator says and the consensus among the fan base is that the non-numbered titles ARE MAINLINE TITLES.
Except that I'm a fan too. There you go gatekeeping again. It is literally a spinoff by definition whether you like it or not. It's objective fact based on the definition of spinoff. That's just what a spinoff is. You can't redefine that to make yourself right in this situation. Speaking of which, why are you so determined to be right here?
Why are you fighting this so hard? What's in it for you? The satisfaction that you're a true KH fan and you defended its honor from a meanie on the internet that loves all the games but considers some of them side stories? Just let me have my view. I know I won't convince you otherwise, even though my view is based on a definition and yours is based on your emotional attachment to the side story games and the fear that if they're spinoffs that somehow delegitimizes them, but if you love the side story games, just love them and stop worrying about it. I'm right there loving them with you.