This depends on the researcher's definitions of 'extremism' and 'conspiracy theories'.
- Recently we've seen many left wing people state that disassembling people in front of their families - surely an 'extreme' act - is a 'beautiful act of resistance', and that calls for genocide against Jewish people (surely also 'extreme') may not constitute hate speech in some contexts.
- For the last 7 years we've had many people believe in the Russiagate conspiracy theory.
- I'm not sure "problematic" has any real meaning.