I can't tell you how many times I've entered into a debate with multiple liberals over the years where they start their response to my argument by saying "LOL that's dumb because reason."
This tool of the Left is used pretty well constantly. It stops people from investigating the realities of liberal claims (see Global Warming). It causes people to refuse to consider legitimate alternative theories to Darwinian Evolution. (As I've said countless times, Darwinian Evolution specifically means macroevolution, that is, change from one species to another over time. This is opposed to microevolution, which is genetic adaptation within the same species i.e. over time dogs develop strong senses of smell and hearing which helps them survive; however these dogs stay dogs.) It causes people to call themselves "moderates" when, in their heart of hearts, they are indeed conservatives but they won't use the appropriate label in order to avoid ridicule.
It's purely a psychological form of debate. The goal is to make one's opponent feel stupid for believing what they believe, thus they back down. This tactic, when used in a public forum, also leads to piling on. If you've ever had a debate on Facebook, this has probably happened to you. Usually one liberal starts in with the ridiculing of the person who disagrees. Then another comes in to join in, making the opposition feel stupid for believing what they believe.
The goal specifically to make you stop debating. What's important to know is that if these liberals had a good argument, they'd probably use that instead. Chances are they don't have a point. They don't have an argument. Facts are the enemy, so these liberals have to circumvent the issue.
Don't surrender to an enemy with wooden guns, my friends. Just be prepared to demand the liberals make an actual argument and back it up with facts. Period.