The reason they're seen as a separate demographic for marketing purposes is because the "far right" has a very specific view of free speech that is largely divorced from:
A) the actual full scope of the problem of censorship in the real world,
B) the actual rights that other people have to freely associate or filter content they find objectionable, and
C) the actual practical ways to increase free speech access.
Ignoring for a second the ideologies these people espouse, purely speaking as a free speech advocate far right people make my job harder, both because they only seem to show up to advocate for free speech in very selective situations, and because most of their ideas on how to preserve free speech are, frankly, really bad.
Most of the far right crowd isn't going to show up to bat for concepts like Net Neutrality, they're not going to be out campaigning against LGBTQ+ or sex censorship. These are the people I see in my timelines cheering on government intervention into public university curriculums. They push dangerous concepts like Section 230 repeals or nationalizing media companies, and some of their more experimental proposals are just blatantly unconstitutional. It's wild to hear proposals from people who claim that they're free speech advocates that would not hold up under almost any Supreme Court ruling. These people also don't have sophisticated ideas on how to handle spam, pornography, or copyright other than to shrug their shoulders and say that the 1st Amendment shouldn't apply to those things. And their big solution to Twitter censorship is to make new centralized platforms that (for now) cater to specifically them; there's nothing realistic or interesting or permanent about what they're proposing. It's a demographic that likes to say that they're pro-free-speech, but in my opinion a lot of that is just thoughtless rhetoric around the fact that they're mad that different people than them now have power to form their own communities and organize their own social campaigns.
So I would not call Gab or Parler bastions of free speech, and it irritates me that those sites steal headlines and place themselves at the center of these debates. Both sites are far right echo chambers filled with a lot of people who's primary experience with censorship begins and ends with the idea that nobody should be allowed to block them on Twitter. And neither site is afraid to engage in its own censorship -- the sites bill themselves as 1st Amendment advocates purely based around who they censor, not because they have compelling or innovative ideas about how to run a community in general.
I'm being a little uncharitable here, but I'm not being very uncharitable. I have almost completely given up trying to engage with far right ideas on free speech, because a significant portion of that demographic is only interested in free speech in ways that personally benefit them, and trying to assemble their views into an internally consistent philosophy has frankly been kind of a giant waste of my time. If you're worried about tech censorship, go donate to Mastodon or Matrix -- projects that are filled with people who are actually thinking about free speech in deep, thoughtful, and practical ways.