Why are Sages fair? Opinions wanted!

[Chazar]

Are sages necessary for competitive MP play? Am I completely screwed if I do not get access to a Library (or LoreMasters, etc.)?
Please state your viewpoint along with detailed reasons in a reply! The poll is merely there to provide a summary.

Let us assume a standard game setting (~10 provinces per player, 40% magic sites, etc.) as a base for discussion.

Why I ask and what I want from you:
I have an impression that access to sages is required for any chance to victory for most nations. Sure, a lot of luck is required to win an MP-game, but must things can be influenced by the player (i.e. willingly choosing between luck and misfortune influences the chances of a razed lab/temple in your captial; one is able to choose whether to send a non-immortal magic-skilled pretender into battle or not, etc). However, I cannot influence the chances of having a library right next door to my captial, especially in non-gigantic maps... This is bad in my view!

So I am wondering about other people's opinion on the impact of sages. I once asked about a mod to reduce the research bonus of sages by 2 points (Post#309766), but what puzzles me is that no one else seems to care at all, so I am looking for reasons why the existence of sages is balanced if not everybody can get them with a 40% magic site frequency or even lower. (I think a 50% magic sites ensures that there will be Library nearby for everybody.) What are reasons to use the mod? What are reasons against using it? Does research difficulty and map size influence the necessity of sages?