"It shouldn't be your responsibility to have to disavow spammy backlinks that other people create. The Google algorithm should take care of this on its own by simply disregarding such backlinks. Otherwise it would be easy for other people to sabotage your site's Google rankings by creating a lot of spammy backlinks to it."
I completely would agree with this. For example, a few domains are pointing hundreds of links to my site. I have updated the disavow file with only top level domains. I can't believe Google wants site owners to do this. Many site owners have precious little time as it is to create content, so then to waste valuable time updating the disavow tool is just not on. If Google recognizes them as bad links, why not just discount them altogether and let people update their disavow tool in their spare time rather drop/reduce their indexing?