There are many, many institutions preforming global IPv4 scans daily and many tools that allow you to do it[0][1][2]. The trick is to "Be a good citizen", work with a scan friendly host, signal your benevolence, and limit the rate at which you scan. Also smart to black-list DoD networks. If you don't believe me setup a honey pot and open up a popular udp amplification port. Haven't done so myself but I would expect many instances of scanning would be seen everyday.

[0]:https://zmap.io/ [1]:https://github.com/robertdavidgraham/masscan [2]:https://memcachedscan.shadowserver.org/

It's rare that abuse reports are handled quickly, and obviously the FBI is using non-attributable ranges for this kind of stuff. The article has a lot of misnomers but the core reporting seems correct. I would be shocked if the FBI (or Cyber Command or whoever) weren't doing port scanning to help secure the Internet by finding vulnerable servers and services.

(I'm sure NSA is, too, but obviously with different objectives.)

you massively overestimate what any ISP is going to do. it's nothing. they're not running honey pots, they don't care.

I think I agree. It's better to not be proactive, especially since port scanning is a natural way to perform diagnostics. I would wait for others tell me there's a problem, I wouldn't put money toward sniffing out problems as an ISP.