I think this is largely a matter of habit, and not of reality. Yes, you might get the business short term if you lie and say some feature will be available Q3. But over time that type of constant lying erodes trust and hurts you.
I get it, you might need to do it to survive in the beginning because competitors will be doing the lying. But I'm saying you need to stop lying as soon as possible for the long term health of the relationship.
I didn't want to quibble about whether it's fair to call it "lying", but I think the term is misleading you. There's simply no such thing as a business relationship without time estimates. It's not a short term vs. long term or trust vs. distrust tradeoff - unless your business model consists entirely of off-the-shelf purchases, your customers will want estimates about what you'll do in the future and when.
I get it, you might need to do it to survive in the beginning because competitors will be doing the lying. But I'm saying you need to stop lying as soon as possible for the long term health of the relationship.