Say you did that. If a third person comes along and goes to PotatoBTC's page, they will not be able to see any of Oshtor's comments on any of Potato's posts. Nor will they see the contents of anything Oshtor quote reposted from Potato, like the screenshot above.
Naturally, you and I will never see anything of each other until you lift the block. But the interesting thing is that no one else can see anything we said to each other. They'd only see one side or the other, depending on who they're looking at.
If I posted a lie and you corrected me, someone would either only see the lie or the correction, but not both together. And vice versa if you posted the truth and I posted a lie in response.
The propagandized population is more likely to be the blocking population. The truth seekers will allow dissenting opinions to stand the test of time and not block people as much. Followers on either side will only see the views of their own side, never the dissenting view.