Comment by ssl-3

Or at least: It's a sign that people were compelled to push a button.

I've seen it happen over and over again when a wireless provider like Verizon or a docsis provider like Spectrum has a widespread outage that is isolated to their service: People push the wrong button.

Verizon issue, other providers fine? Verizon spikes on downdetector, but so do reports of AT&T and T-Mobile problems.

Same with Spectrum: When it's screwed up for whatever reason, reports for other ISPs also spike.

This happens even when those other systems are completely unaffected and working just fine.

Downdetector does provide useful data, but it's not necessarily clean data that establishes anything clear on its own.