Was Cesare really capable of conquering Italy without assassin interference? What was the extent of Ezio's impact over the brotherhood? Did the brotherhood become global thanks to Altaïr, Ezio, or neither?
Some parts of this post will seem like ragebait, but I promise it's not.
Ezio is canonically one of the most important assassins (that's a debate to be had honestly, but when it comes to how influential they were to the brotherhood, Ezio is generally considered second only to Altaïr and maybe Bayek).
Anyhow, maybe this is just me misremembering stuff, it has been a while since I played the Ezio trilogy, but were the Borgia really that big of a threat in the first place? Compared to the likes of the British Empire and Abstergo, their concerns and plans seem a lot more local.
No doubt breaking the power of such a strong branch of the Templar Order was impressive, but it doesn't seem as important as some other feats from other assassins.
Thomas de Carneillon broke templar power in all of Europe for a century, Connor singlehandedly expelled the templars from the colonies after they had decades to consolidate their power, the Frye twins freed London from centuries of templar control in a single year.
Ezio and Altaïr are the 2 emblematic figures that made the brotherhood what it is, and again, I'm probably misremembering something, but compared to Altaïr, Ezio's impact seems a bit smaller.
Did the brotherhood become a global thing thanks to Altaïr, Ezio, or was it global before either of them? Honestly, the games after Syndicate made that aspect of the lore a bit confusing to me.