Agreed, that's why I've always thought of it as an implied valuation. Investors are going into it expecting upside, and the terms allow them to have a floor (regardless of what happens with common/ prior rounds), but I don't think they would make the investment if they felt an acquisition/ IPO/ other liquidity event would value each share of the company at less than what they paid for it. I don't think its unreasonable to use this to get to an implied total valuation.