I don't post Slashdot links much here, since they're generally summarizing another site, but in this case, I think they explain it better than the link. The tl;dr is that a bunch of browsers as basically hosed if people try to use them on Cloudflare sites (and it's not like you can really avoid hitting CF sites). The only browser listed here that I've used a bunch is Seamonkey, but I do like trying new browsers periodically, and this is crappy for any developers of them.