I think where you are misunderstanding (or disagreeing) is what is a “ritual”, and it’s due to the nature of Judaism since the Romans destroyed the Temple.
You are interpreting “ritual” broadly. If, for example, one considers every bris a “ritual”, then, sure numerically, many more “rituals” have always been held outside the Temple.
If you are interpreting “ritual” in the more traditional fashion to mean the Aaronic duties of Passover sacrifice and the like, then, no, Jerusalem has always been the center.
Since we’re talking about “most rituals... before the destruction of the Second Temple,” I think it’s very reasonable to presume the sort of rituals which went on within the Temple. The presence of ritual baths associated with the local synagogues indicate the existence of rituals outside the Temple. Now, keep in mind, I’m interpreting the meaning used in the article here: The rituals permitted only in the Temple? No, but that would indicate the sort of tautology which must be excluded by “most.”