There's a lot of mistaken assumptions and misinformation here about Parler; it looks like most of the commenters haven't actually used it, or have only given it a cursory glance. To wit:
1. Parler is actively recruiting liberals and moderates, to build a "big tent" of diverse opinions and perspectives.
2. The moderation guidelines are quite explicit: don't censor anyone for expressing a political opinion of any sort. Don't censor people you disagree with. Do moderate extremely toxic content -- but it has to be pretty clear, like "I'm going to kill you" or a stream of expletives with zero redeeming content. Or spam, or nonsensical posts.
3. The parleys (their version of tweets) are largely sociopolitical commentary of the type that's being downvoted or censored on the major platforms like Twitter and Facebook. For example, you can post freely about hydroxychloroquine as an effective treatment for covid19. You can say "The 2020 Election was stoken". Pretty much all of the "3rd rail" topics that have been restricted elsewhere. You can link to an article by Alex Jones or Q. Their attitude seems to be, read and decide for yourself.
4. Competition is a good thing. A lot of people here have a reflexive notion that "fringe" sites like Parler and Gab will just create more echo chambers to keep "those people" ignorant. Nothing could be farther from the truth. Giving people a free speech platform is a breath of fresh air, a return to a broader and more civil discourse. Censorship does not encourage civility; it does not foster broadminded attitudes. On the contrary, it causes more extremism.