they wouldn't be supporting Trump in the first place

Not necessarily. A significant number of them could be informed about his stances and agree with him. And you think a bunch of strawman arguments and namecalling will convince any of his supporters (irrational ones or not) to change their minds? Of course not. It just makes liberals look bad and if anything encourages his supporters to be more vocal about Trump.

The whole Drumpf nonsense reminds me of some grade school child making fun of another kid's name. Its completely embarrassing, arguably on an equal level of Trump's embarrassing rhetoric.