Depending on what the debate is about, winning it can be meaningful. There are very little cons that come from winning a debate, with only hurting some ones feelings. While winning a debate can further a political career amongst many other things, so it can be very meaningful for the winner.
Winning a debate is meaninful because it shows that person's strengths and charisma. It makes the winner feel good because they were able to properly present their side of the argument and deliver it in a way that made others understand them clearly and even at times agree with them.