In this case you have to see the world "suki" as a japanese person. For a japanese, it doesn't end in "i", it ends in "ใ" (ki). The adjective needs to end in a hiragana ใ to be considered an i-adjective. And of course, there are a few exceptions like "kirei" that ends in ใ, but is a na-adjective.
In this case you have to see
In this case you have to see the world "suki" as a japanese person. For a japanese, it doesn't end in "i", it ends in "ใ" (ki). The adjective needs to end in a hiragana ใ to be considered an i-adjective. And of course, there are a few exceptions like "kirei" that ends in ใ, but is a na-adjective.