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.
Winning a debate is just like winning a competition. It requires the skill of how you present yourself and how can you prove your arguments.
I've won a parliamentary debate where I had to support the motion "cigarette should NOT be banned", though I strongly feel it should be :-0
The point is winning such debates have no meaning in practical life.
The outcome of a debate should bring some positive changes in the society, numerous debates take place on numerous serious issues, but hardly any implementation takes place, thus, rendering winning a debate as completely meaningless.