For me, #1 is tracking, #2 is malware.

chopin · on April 4, 2016

It comes close as a #2 for me (I care more for an uncompromised system than for tracking but YMMV). However, the article states that the state of affairs might be better for publishers if they didn't ignore DNT. I doubt that very much for these two reasons:

1. Malware 2. Intrusive ads, even the article site serves animated ads which distract from the content.

phineastcat · on April 4, 2016

For me, #1 is the extra bandwidth cost (I have a crappy internet connection), #2 is malware, and #3 is tracking.

My crappy internet connection is what originally pushed me to block ads. Everything's a lot more speedy when you're not loading all those extra scripts, images, and videos.