Net abbreviations had appeared first in English even before the Internet became what it is now, i.e. before WWW (world-wide-web).
20 years ago people were using dialup modems (btw, modem is an acronym too from modulator-demodulator) and bulletin board systems (BBS), obviously, abbreviations were the result of people laziness (to a degree). First BBSs appeared in the US so it's only natural that these abbreviations were in English. When these systems appeared in Russia we used all these BTW, FYI, RTFM, AFAIK, IMHO, ASAP, etc just because they were de-facto standard and there was no reason to invent our own ones since everyone else seemed to understand them.