Someone last week framed the SAFE agreement as kind of like a union for founders, catalyzed by YC.

When an investor and a founder are haggling, the investor has the upper hand because they've done 100 or 1000x more deals than the founder has.

They have the relevant knowhow, and the founder does not.

A SAFE says "here's a widely agreed upon schelling point that everyone finds reasonable, no need for haggling."

The more that everyone just uses a SAFE, the more that anyone who doesn't will look suspicious, and feel compelled to.