Where's that requirement found? Not saying I doubt it exists, I just can't locate it from a quick browse through Annex 15/Doc 8400 and I'm curious by nature.
Regarding the copying algorithms, you'll have to blame Naviair (which you link in SkyAngel) and not Google Chrome. It's the Naviair site which (re)publishes the NOTAMs without any newlines at all, as the NOTAM page is an HTML table rather than raw text. This gives browsers a lot of freedom to implement the copying any old way they please, regardless of what ICAO says.
As a user, I kindly request this feature in order to be able to use my standard browser in conjunction with your software. ICAO compliant or not, the current implementation hampers the usability of the software.
Ideally, we'd have access to the raw NOTAM feeds for every FIR in the world but looking at it realistically, you'll have users copying NOTAM text from pretty much any source they can get their hands on. Strict enforcement of the data format will mean lots of frustrated users around the world. This far, it's just luck that IE copies tables in a (non-ICAO-compliant) format which the parser can handle.
Cheers,
/Fred