I signed up for Parler 6 weeks ago and what I have seen from the platform is frightening. It isn't dumb memes and gifs but hardcore alt-right propaganda and conspiracy theories.
Within hours of commenting on posts I was contacted about joining groups of "like minded patriots" (their actual words). This lead to Telegram and Discord servers dedicated to "their cause". These places are highly organised. Unique URLs with multiple 'decoy and delay' steps to find and remove people from sharing links with authorities for example.
They have detailed (probably some of the best tbh) guides on signing up for secure services like Protonmail for email, installing Tor and Tails to access Onion services (this leads to a whole other world of horrors), how to use Bitcoin to purchase what are essentially burner SIM cards and phones to sign up to other services, and advice on how to recruit your friends and family such as conversation topics and “gotcha” responses, manipulated media to share, psychological and emotional manipulation techniques, etc.
The techniques used are no different to what we have seen from groups like ISIS/ISIL over the past decade.
I support free speech but this goes beyond that IMHO. This isn't strongly disagreeing with government policies but clearly talking about murdering those they believe are wrong. I have seen people seriously talking about kidnapping and murdering politicians. Posting photos of their weapons. Sharing detailed instructions on homemade chemical weapons and IEDs from people who clearly have military knowledge of such things.
When ISIS was releasing daily videos of horrific murders everyone called for such recruitment platforms to be shut down. It wasn't a matter of free speech then and it isn't now. The only difference is that these are (mostly) white American and European people not brown people from the middle east. The message and methodologies used are the same though.
Parler is without question a platform for radicalisation and recruitment for "western jihad" as I have seen people un-ironically use. It needs to go and I fully support Amazon, Apple, Google and whoever else in shutting them down.