Because LPs increasingly treat **fairness and transparency** as core underwriting issues.

- Favorable side letters can create **unequal economics, control rights, or reporting burdens** across LPs.
- That can hurt trust, make the fund harder to explain, and create operational complexity.
- For emerging managers, bespoke side-letter obligations can even **reduce performance** by consuming time and resources.
- So newer LPA language often tries to **limit preferential treatment**, while still allowing narrow LP-specific exceptions like tax, regulatory, or compliance needs.

In practice, the goal is not to ban all side letters, but to keep them **rare, narrow, disclosed, and non-distorting**.

References:
- https://decilegroup.com/articles/venture-capital-transparency
- https://decilegroup.com/articles/institutional-money-hurt-your-fund
- https://decilehub.com/base/1-general_questions/163952-on-side-letters-in-8-3-cornerstone-lpa