Mark told me "Building great products is about making choices."
While he did not elaborate too much on what it means - here's my take:
A critical role product managers play is acting as a communication hub on product-related matters. That means the product manager will have to seek and understand stakeholders' / customers' needs and wants. While taking everybody's point into consideration, it is very easy to fall into the trap of "trying to be everything for everybody".
As a product manager, very often we have to make tough choices and be accountable for it. I can't think of any successful product that is "everything to everybody" - the only one that come very close is Google.
Microsoft isn't behaving like that anymore - they have, imho, recognized the space of opensource development.
Apple isn't like that - they know who their fans are.
Southwest, Air Asia - they made their choice first, then their customers chose them.
A leader is always the one who made choices and live up to it. It's OK to fail - but fail fast and move on :)