You're wrong, sorry to have to break it to you.
If someone is reading the bread, filtering is helpful by deleting comments from people who you know you are not interested in hearing from. If the person is, for instance, stupid, filtering them saves the time of reading all the stupid words they type.
Filter+ is useful for those times when an obvious shill is wasting time and anons who are either stupid or newfags are responding. FE shills for instance. Deleting everyone involved in those conversations raises the IQ of the thread by 20 percent.
So if someone has limited time to spend here, the filter is one of the most important aspects of the software.