Youtube is run by a bunch of leftist cucks. One of the big vloggers on there, Philip DeFranco, got left out of their 2016 Youtube Rewind video in a fit of spite because he refused to endorse Hillary in one of his videos.
True; but they are also a business, and given half the country voted for Trump, might not be the best business plan to turn a blind eye to anti-Trump defamation and threats.
It is possible for Leftists to decide that propaganda and re-education of the unwashed masses is worth the loss of money and customers.
However if they went that route it would only lead to one of their rival services be able to adopt opposing policy and become a significant rival to them.
Quora had initially that same kind of phenomena as it was started by leftoids in LA who initially recruited their leftoid friends. As a consequence Brexit was essentially worshipping the satan on massive scale by hillbilly britons and Trump's choice would lead to military attacking White House to depose of him in order to avoid the end of everything.
They also had several conservatives banned from the site and their answers collapsed because they were trying to rationalize with the left and offer the conservative take on all of it which is of course strictly forbidden and to be fought.
Regardless the conservatives have now learnt on Quora not to answer trollish anonymous questions like "What does [name] think of Trump's [action]?".
One of the funniest are the type of questions which ask something like "How awful is Trump?" and if anyone answers that he isn't then their answers get collapsed by a swarm of downvotes while only tolerating answers that go with their own narrative.
The conservatives still manage to persist and grow in numbers as they're learning to avoid some of the worst traps. There's already a decent sized number of well written and followed conservatives there, one of my personal favorites is Jon Davis who coincidentally is a marine. Must be pure coincidence!