Molten salt reactors is a nightmare for material science. You effectively have half of Mendeleev's table on your hands and it's borderline impossible to design a material which will have enough corrosion resistance (reactors have to serve at least several decades) and don't forget about high levels of radiation as well, which also contributes to material damage. Plus online fuel processing is much more difficult than the fuel processing required for fast breeder reactors, and it's one of the main stumbling blocks for breeders right now (well, judging by Russian's experience).

Inertia of the industry combined with risk aversion. Nuclear regulation is not really setup for small modular reactors and nuclear power still has a bad name.

The nuclear fanboys still push the big reactors. I think renewable fans like me favor next gen rectors because we are okay with not building reactors right away. We can build renewables until they are developed. Nuclear fans OTOH hate renewables and just want to build whatever is possible right now.

So we are in a situation where nuclear fans are not pushing it and most renewable fans think all nuclear power is like the current shitty big reactors.

I see, so we can quickly build cheap & safe small molten salt reactors but we actually don't build because of risk aversion and industry inertia so that's really a shame (I thought the tech just wasn't ready yet).

Another problem is nuclear fanboys: why exactly do they hate renewables so much ?

I'm a nuclear fanboy, and I don't hate renewables. Nor do I know anybody who does. We just want nuclear to be allowed. After that, of course it's a matter of results. But currently the narrative is that "we don't want nuclear, because we have renewables"