I think perhaps you're underappreciating the difficulty of physical distribution. Having one's voice heard has always been the domain of the rich and powerful. Sure, platforms control promotion and discoverability today, but I doubt that gives them more strength to control dissenting views than was available in the days of the printing press.
It's a heck of a lot harder to effectively eradicate physical media than digital.
F.ex. if I shower a town with 250 physical leaflets + I post on all the major platforms, and immediately people of power attempt to suppress them, which do you think results in more people seeing them?
Well I think it depends on the situation. If you're trying to post something they have already built good defenses against (e.g. child porn, or maybe mocking the king of Thailand), you'd probably have better luck with the handbills, but then you'd also have a better chance of getting arrested. If you are posting something that isn't automatically suppressed, I bet social media would still get you more reach.
You're missing the third option however. Start your own blog, then just post links on all of the major social medias, and especially on some of the minor ones. Once your link hits the right Signal groups or Truth Social followers or whatever, it will fly around way faster than any samizdat ever could.
The internet / web has never been a platform where all had equal access to share their views. The ability to speak doesn't matter if few can hear you.
When it was more democratic in the early days, the masses weren't part of it.
When the masses came online, promotion and discoverability had already been centralized by large platforms.