A few days ago, a writer on Facebook was asking for feedback on his 72 word logline, which was weighted down with too much detail. I wrote the person a better logline in five minutes with half the words. The writer seemed upset because I tried to teach them that the logline should contain whats at stake for the protagonist. I also emphasized that if their logline doesn't pass muster, few industry people would be interested in reading their script.
In crafting a logline that's an intriguing one sentence summary of your story, you're providing the potential reader with some comfort that if they invest time in reading your screenplay, it won't be a waste of time.
A few weeks back, I submitted a logline to five recipients. Two of them requested the script. Bada Bing!