at a higher level of play, there is such thing as an auto win
Please give me an example of a top D3 face a top DK, and the DK winning in a tourney where the Infinite is Not Banned or the top pikas and a top fox.
Some matches are that horrible that it is basically impossible. (you can call it 99 to 1 but really, is it that meaningful?)
I understand people saying to avoid the ice climber infinite because that is true. Ice climbers have 0 to deaths besides this and the only way to beat them in melee is to kill Nana and its exactly the same in brawl besides the fact that Popo can't Kill as well and that Nana has slightly better AI.
The difference for D3 is that D3 has such a humongous range. DK's cannot avoid grabs.
Also, for any wall infinite, most wall stages are banned, if you are afraid, block out that CP, or just avoid it when it does occur like on PS1 or Delfino until its not there anymore. These can be avoided by just dodging for a while.
Other strategies such as laser locks can be avoided by learning how to Tech better.
This is the reason why so many people are in favor of banning the D3 infinite. Furthermore, many tournaments already ban the short step infinite. Just look at the majority of East Coast tourneys.