Not only for topics that are suppressed, but also topics that are very niche. I played around with yacy to crawl for documentation of mechanical switches for my project - keycomp.co. It is awesome that you can just put few websites that you want to crawl, even edit its robots.txt and collect all of the data you need. Only issue is that it is very easy to just run out of storage, and even if you have that problem under control, there is an issue with yacy randomly crashing.