If I tell a guy to make me a table, and he puts his heart and soul into making me a beautiful wooden dining table, then when he shows it to me I tell him I actually wanted a glass coffee table and would he please start over from scratch, throwing his work away will be very bad for his morale.
That's not to say requirements can't change - of course they can. But they shouldn't change just because I forgot to make myself clear the first time.
If you're leading a software team, championing a clear definition of "done" for the team and business partners (usually collaboratively). Other teams have analogous targets. There are some teams where the "work" resists completion.
That's not to say requirements can't change - of course they can. But they shouldn't change just because I forgot to make myself clear the first time.