Liquidation preference of 1x (or lower) is just sensible alignment of investor and founder incentives. The investor wants to make sure that if they buy 20% of the company for $5M, the founders aren't now incented to take advantage of them (in an extreme example: the day after the fundraising, liquidating the company for its assets, taking home $4M themselves and handing the investor back $1M. In a less extreme example, selling the company (in toto) for $10M a year or two later).
Liquidation preference of higher than 1x is a whole different thing. It's, at its most benign, something kind of like a financial instrument a little more like debt than stock, trading a more-guaranteed return for a lower price, or at its most pernicious, basically an attempt to create false impressions of a company's value. If you sell stock with a x3 liquidation preference, that is deeply different, and conveys considerably less investor confidence, than selling the same stock at the same price with x1 liquidation preference, but the press releases get to not mention the preference.