Speaking from my own perspective of running general tech job boards [1], I would say that too narrow job boards have a really short lifespan.
This is because, you need a good supply of fresh offers to keep the audience. So if you end up to niche, you quickly become a job-ad-graveryard. Unless you scrap other big job sites automatically and somehow manage to filter and classify the jobs based on your niche.
Agreed. It's like single issue political parties. They make a point and then will disappear once people realise that a strong feeling about just one issue is actually a very small statement overall.
I guess I'd like to see this job board refocus to be a curated set of jobs, that are chosen by a group of technical experts and those who are trusted to vouch for good company cultures. It may be that no cryptocurrency jobs get through that filter! That may even be an unwritten rule. But the fact that it's not the tagline of the whole site would hopefully make it more impactful in the long run.
This is because, you need a good supply of fresh offers to keep the audience. So if you end up to niche, you quickly become a job-ad-graveryard. Unless you scrap other big job sites automatically and somehow manage to filter and classify the jobs based on your niche.
[1] https://devitjobs.uk and https://devitjobs.us