Or they'd decrease because people would actually be able to see the counterarguments to that propaganda. As it currently stands, very few people are able to produce the counter-propaganda because few have access to the actual propaganda.
This phenomena is how I've been mostly converted to racism (well, HBD), I could, with some difficulty, find the pro-racism view but finding an anti-racist view that actually addressed the HBD view was basically impossible (what little anti-racist stuff there was mostly attacking strawmen) because basically no one is exposed to the HBD argument (thanks to censorship including social censorship mostly), so no one produces counterarguments!
Also, there's a small chance that I've been completely mislead about what the supposed "Islamic terrorists" believe and actually their ideology is awesome and I should convert to wahabiism. I'd like the opportunity to make that decision myself.